21715900 has 36 divisors (see below), whose sum is σ = 47328568. Its totient is φ = 8648640.

The previous prime is 21715891. The next prime is 21715907. The reversal of 21715900 is 951712.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21715907) 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, 39427 + ... + 39973.

Almost surely, 2^21715900 is an apocalyptic number.

21715900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21715900 is an abundant number, since it is smaller than the sum of its proper divisors (25612668).

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

21715900 is a wasteful number, since it uses less digits than its factorization.

21715900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 958 (or 951 counting only the distinct ones).

The product of its (nonzero) digits is 630, while the sum is 25.

The square root of 21715900 is about 4660.0321887300. The cubic root of 21715900 is about 278.9925529973.

The spelling of 21715900 in words is "twenty-one million, seven hundred fifteen thousand, nine hundred".