21537712 has 40 divisors (see below), whose sum is σ = 48179456. Its totient is φ = 9135936.

The previous prime is 21537689. The next prime is 21537743. The reversal of 21537712 is 21773512.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10603 + ... + 12469.

Almost surely, 2^21537712 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21537712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24089728).

21537712 is an abundant number, since it is smaller than the sum of its proper divisors (26641744).

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

21537712 is a wasteful number, since it uses less digits than its factorization.

21537712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1985 (or 1979 counting only the distinct ones).

The product of its digits is 2940, while the sum is 28.

The square root of 21537712 is about 4640.8740556063. The cubic root of 21537712 is about 278.2273729437.

The spelling of 21537712 in words is "twenty-one million, five hundred thirty-seven thousand, seven hundred twelve".