21566452 has 12 divisors (see below), whose sum is σ = 38958976. Its totient is φ = 10435320.

The previous prime is 21566437. The next prime is 21566453. The reversal of 21566452 is 25466512.

It is a super-2 number, since 2×21566452² = 930223703736608, which contains 22 as substring.

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21566453) 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, 86838 + ... + 87085.

Almost surely, 2^21566452 is an apocalyptic number.

It is an amenable number.

21566452 is a deficient number, since it is larger than the sum of its proper divisors (17392524).

21566452 is a wasteful number, since it uses less digits than its factorization.

21566452 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173958 (or 173956 counting only the distinct ones).

The product of its digits is 14400, while the sum is 31.

The square root of 21566452 is about 4643.9694228106. The cubic root of 21566452 is about 278.3510738052.

The spelling of 21566452 in words is "twenty-one million, five hundred sixty-six thousand, four hundred fifty-two".