21645652 has 18 divisors (see below), whose sum is σ = 44064762. Its totient is φ = 9276624.

The previous prime is 21645619. The next prime is 21645683. The reversal of 21645652 is 25654612.

It can be written as a sum of positive squares in only one way, i.e., 20196036 + 1449616 = 4494^2 + 1204^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 55023 + ... + 55414.

Almost surely, 2^21645652 is an apocalyptic number.

It is an amenable number.

21645652 is an abundant number, since it is smaller than the sum of its proper divisors (22419110).

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

21645652 is a wasteful number, since it uses less digits than its factorization.

21645652 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110455 (or 110446 counting only the distinct ones).

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

The square root of 21645652 is about 4652.4887963326. The cubic root of 21645652 is about 278.6913936326.

The spelling of 21645652 in words is "twenty-one million, six hundred forty-five thousand, six hundred fifty-two".