21537732 has 12 divisors (see below), whose sum is σ = 50254736. Its totient is φ = 7179240.

The previous prime is 21537689. The next prime is 21537743. The reversal of 21537732 is 23773512.

It is a tau number, because it is divible by the number of its divisors (12).

It is a self number, because there is not a number n which added to its sum of digits gives 21537732.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 897394 + ... + 897417.

Almost surely, 2^21537732 is an apocalyptic number.

It is an amenable number.

21537732 is an abundant number, since it is smaller than the sum of its proper divisors (28717004).

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

21537732 is a wasteful number, since it uses less digits than its factorization.

21537732 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1794818 (or 1794816 counting only the distinct ones).

The product of its digits is 8820, while the sum is 30.

The square root of 21537732 is about 4640.8762103723. The cubic root of 21537732 is about 278.2274590646.

The spelling of 21537732 in words is "twenty-one million, five hundred thirty-seven thousand, seven hundred thirty-two".