21565492 has 12 divisors (see below), whose sum is σ = 40642756. Its totient is φ = 9953280.

The previous prime is 21565483. The next prime is 21565493. The reversal of 21565492 is 29456512.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 12348196 + 9217296 = 3514^2 + 3036^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21565493) 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, 207309 + ... + 207412.

Almost surely, 2^21565492 is an apocalyptic number.

It is an amenable number.

21565492 is a deficient number, since it is larger than the sum of its proper divisors (19077264).

21565492 is a wasteful number, since it uses less digits than its factorization.

21565492 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 414738 (or 414736 counting only the distinct ones).

The product of its digits is 21600, while the sum is 34.

The square root of 21565492 is about 4643.8660618067. The cubic root of 21565492 is about 278.3469436096.

The spelling of 21565492 in words is "twenty-one million, five hundred sixty-five thousand, four hundred ninety-two".