21772 has 6 divisors (see below), whose sum is σ = 38108. Its totient is φ = 10884.

The previous prime is 21767. The next prime is 21773. The reversal of 21772 is 27712.

It is an Ulam number.

It is a plaindrome in base 6.

It is not an unprimeable number, because it can be changed into a prime (21773) by changing a digit.

21772 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2718 + ... + 2725.

2²¹⁷⁷² is an apocalyptic number.

It is an amenable number.

21772 is a deficient number, since it is larger than the sum of its proper divisors (16336).

21772 is a wasteful number, since it uses less digits than its factorization.

21772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5447 (or 5445 counting only the distinct ones).

The product of its digits is 196, while the sum is 19.

The square root of 21772 is about 147.5533801714. The cubic root of 21772 is about 27.9232592534.

It can be divided in two parts, 217 and 72, that added together give a square (289 = 17²).

The spelling of 21772 in words is "twenty-one thousand, seven hundred seventy-two", and thus it is an iban number.