21478572 has 36 divisors (see below), whose sum is σ = 54532296. Its totient is φ = 7128000.

The previous prime is 21478553. The next prime is 21478579. The reversal of 21478572 is 27587412.

21478572 is a `hidden beast` number, since 2 + 14 + 78 + 572 = 666.

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

It is a super-2 number, since 2×21478572² = 922658110318368, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21478579) 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, 7848 + ... + 10224.

It is an arithmetic number, because the mean of its divisors is an integer number (1514786).

Almost surely, 2^21478572 is an apocalyptic number.

It is an amenable number.

21478572 is an abundant number, since it is smaller than the sum of its proper divisors (33053724).

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

21478572 is a wasteful number, since it uses less digits than its factorization.

21478572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2638 (or 2633 counting only the distinct ones).

The product of its digits is 31360, while the sum is 36.

The square root of 21478572 is about 4634.4980310709. The cubic root of 21478572 is about 277.9724797215.

The spelling of 21478572 in words is "twenty-one million, four hundred seventy-eight thousand, five hundred seventy-two".