21537612 has 36 divisors (see below), whose sum is σ = 55138720. Its totient is φ = 7087392.

The previous prime is 21537601. The next prime is 21537613. The reversal of 21537612 is 21673512.

It is a happy number.

21537612 is a `hidden beast` number, since 2 + 15 + 37 + 612 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is not an unprimeable number, because it can be changed into a prime (21537613) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 943 + ... + 6630.

Almost surely, 2^21537612 is an apocalyptic number.

It is an amenable number.

21537612 is an abundant number, since it is smaller than the sum of its proper divisors (33601108).

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

21537612 is a wasteful number, since it uses less digits than its factorization.

21537612 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7662 (or 7657 counting only the distinct ones).

The product of its digits is 2520, while the sum is 27.

The square root of 21537612 is about 4640.8632817613. The cubic root of 21537612 is about 278.2269423380.

The spelling of 21537612 in words is "twenty-one million, five hundred thirty-seven thousand, six hundred twelve".