21762 has 32 divisors (see below), whose sum is σ = 53760. Its totient is φ = 6480.

The previous prime is 21757. The next prime is 21767. The reversal of 21762 is 26712.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21757) and next prime (21767).

21762 is an astonishing number since 21762 = 62 + ... + 217.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a plaindrome in base 15.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 21762.

It is not an unprimeable number, because it can be changed into a prime (21767) by changing a digit.

21762 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 687 + ... + 717.

It is an arithmetic number, because the mean of its divisors is an integer number (1680).

2²¹⁷⁶² is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21762, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26880).

21762 is an abundant number, since it is smaller than the sum of its proper divisors (31998).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21762 is a wasteful number, since it uses less digits than its factorization.

21762 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55 (or 49 counting only the distinct ones).

The product of its digits is 168, while the sum is 18.

The square root of 21762 is about 147.5194902377. The cubic root of 21762 is about 27.9189834962.

Subtracting 21762 from its reverse (26712), we obtain a triangular number (4950 = T₉₉).

It can be divided in two parts, 2 and 1762, that added together give a square (1764 = 42²).

The spelling of 21762 in words is "twenty-one thousand, seven hundred sixty-two".