21432645 has 24 divisors (see below), whose sum is σ = 40008696. Its totient is φ = 10551168.

The previous prime is 21432629. The next prime is 21432661. The reversal of 21432645 is 54623412.

21432645 is a `hidden beast` number, since 2 + 14 + 3 + 2 + 645 = 666.

It is an interprime number because it is at equal distance from previous prime (21432629) and next prime (21432661).

It can be written as a sum of positive squares in 4 ways, for example, as 60516 + 21372129 = 246^2 + 4623^2 .

It is not a de Polignac number, because 21432645 - 2⁴ = 21432629 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17734 + ... + 18903.

It is an arithmetic number, because the mean of its divisors is an integer number (1667029).

Almost surely, 2^21432645 is an apocalyptic number.

It is an amenable number.

21432645 is a deficient number, since it is larger than the sum of its proper divisors (18576051).

21432645 is a wasteful number, since it uses less digits than its factorization.

21432645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36661 (or 36658 counting only the distinct ones).

The product of its digits is 5760, while the sum is 27.

The square root of 21432645 is about 4629.5404739564. The cubic root of 21432645 is about 277.7742115394.

The spelling of 21432645 in words is "twenty-one million, four hundred thirty-two thousand, six hundred forty-five".