21570020 has 24 divisors (see below), whose sum is σ = 45628800. Its totient is φ = 8564832.

The previous prime is 21570019. The next prime is 21570041. The reversal of 21570020 is 2007512.

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, 1100 + ... + 6659.

It is an arithmetic number, because the mean of its divisors is an integer number (1901200).

Almost surely, 2^21570020 is an apocalyptic number.

21570020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21570020 is an abundant number, since it is smaller than the sum of its proper divisors (24058780).

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

21570020 is a wasteful number, since it uses less digits than its factorization.

21570020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7907 (or 7905 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 17.

The square root of 21570020 is about 4644.3535610459. The cubic root of 21570020 is about 278.3664232913.

Adding to 21570020 its reverse (2007512), we get a palindrome (23577532).

The spelling of 21570020 in words is "twenty-one million, five hundred seventy thousand, twenty".