21763 has 4 divisors (see below), whose sum is σ = 24880. Its totient is φ = 18648.

The previous prime is 21757. The next prime is 21767. The reversal of 21763 is 36712.

It is a semiprime because it is the product of two primes.

It is a de Polignac number, because none of the positive numbers 2^k-21763 is a prime.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 21763.

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

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1548 + ... + 1561.

It is an arithmetic number, because the mean of its divisors is an integer number (6220).

2²¹⁷⁶³ is an apocalyptic number.

21763 is a deficient number, since it is larger than the sum of its proper divisors (3117).

21763 is an equidigital number, since it uses as much as digits as its factorization.

It is an anagram of its base 9 representation: 21763 = (32761)₉.

21763 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3116.

The product of its digits is 252, while the sum is 19.

The square root of 21763 is about 147.5228795814. The cubic root of 21763 is about 27.9194111309.

It can be divided in two parts, 21 and 763, that added together give a square (784 = 28²).

The spelling of 21763 in words is "twenty-one thousand, seven hundred sixty-three".