21572730 has 40 divisors (see below), whose sum is σ = 58008852. Its totient is φ = 5752512.

The previous prime is 21572729. The next prime is 21572753. The reversal of 21572730 is 3727512.

21572730 is a `hidden beast` number, since 21 + 572 + 73 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 20007729 + 1565001 = 4473^2 + 1251^2 .

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 21572694 and 21572703.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 12507 + ... + 14126.

Almost surely, 2^21572730 is an apocalyptic number.

21572730 is an abundant number, since it is smaller than the sum of its proper divisors (36436122).

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

21572730 is a wasteful number, since it uses less digits than its factorization.

21572730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26652 (or 26643 counting only the distinct ones).

The product of its (nonzero) digits is 2940, while the sum is 27.

The square root of 21572730 is about 4644.6453040033. The cubic root of 21572730 is about 278.3780805424.

The spelling of 21572730 in words is "twenty-one million, five hundred seventy-two thousand, seven hundred thirty".