21500900 has 36 divisors (see below), whose sum is σ = 46924080. Its totient is φ = 8551200.

The previous prime is 21500893. The next prime is 21500939. The reversal of 21500900 is 900512.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20591 + ... + 21609.

Almost surely, 2^21500900 is an apocalyptic number.

21500900 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 21500900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23462040).

21500900 is an abundant number, since it is smaller than the sum of its proper divisors (25423180).

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

21500900 is a wasteful number, since it uses less digits than its factorization.

21500900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1244 (or 1237 counting only the distinct ones).

The product of its (nonzero) digits is 90, while the sum is 17.

The square root of 21500900 is about 4636.9062962281. The cubic root of 21500900 is about 278.0687682471.

The spelling of 21500900 in words is "twenty-one million, five hundred thousand, nine hundred".