21700520 has 32 divisors (see below), whose sum is σ = 49268520. Its totient is φ = 8601600.

The previous prime is 21700513. The next prime is 21700529. The reversal of 21700520 is 2500712.

It can be written as a sum of positive squares in 4 ways, for example, as 11600836 + 10099684 = 3406^2 + 3178^2 .

It is not an unprimeable number, because it can be changed into a prime (21700529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2120 + ... + 6920.

Almost surely, 2^21700520 is an apocalyptic number.

21700520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21700520 is an abundant number, since it is smaller than the sum of its proper divisors (27568000).

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

21700520 is a wasteful number, since it uses less digits than its factorization.

21700520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4925 (or 4921 counting only the distinct ones).

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

The square root of 21700520 is about 4658.3816932493. The cubic root of 21700520 is about 278.9266731756.

The spelling of 21700520 in words is "twenty-one million, seven hundred thousand, five hundred twenty".