21675564 has 18 divisors (see below), whose sum is σ = 54791100. Its totient is φ = 7225176.

The previous prime is 21675559. The next prime is 21675571. The reversal of 21675564 is 46557612.

It is a happy number.

21675564 is a `hidden beast` number, since 21 + 6 + 75 + 564 = 666.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 602099 = 21675564 / (2 + 1 + 6 + 7 + 5 + 5 + 6 + 4).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 301014 + ... + 301085.

It is an arithmetic number, because the mean of its divisors is an integer number (3043950).

Almost surely, 2^21675564 is an apocalyptic number.

It is an amenable number.

21675564 is an abundant number, since it is smaller than the sum of its proper divisors (33115536).

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

21675564 is a wasteful number, since it uses less digits than its factorization.

21675564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 602109 (or 602104 counting only the distinct ones).

The product of its digits is 50400, while the sum is 36.

The square root of 21675564 is about 4655.7023100710. The cubic root of 21675564 is about 278.8197085476.

The spelling of 21675564 in words is "twenty-one million, six hundred seventy-five thousand, five hundred sixty-four".