21972500 has 120 divisors (see below), whose sum is σ = 56681856. Its totient is φ = 7360000.

The previous prime is 21972497. The next prime is 21972529. The reversal of 21972500 is 527912.

It is a nialpdrome in base 5.

It is a self number, because there is not a number n which added to its sum of digits gives 21972500.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 467477 + ... + 467523.

Almost surely, 2^21972500 is an apocalyptic number.

21972500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21972500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28340928).

21972500 is an abundant number, since it is smaller than the sum of its proper divisors (34709356).

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

21972500 is a wasteful number, since it uses less digits than its factorization.

21972500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99 (or 82 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 26.

The square root of 21972500 is about 4687.4833333037. The cubic root of 21972500 is about 280.0871327464.

The spelling of 21972500 in words is "twenty-one million, nine hundred seventy-two thousand, five hundred".