21506524900 has 144 divisors (see below), whose sum is σ = 58929728256. Its totient is φ = 6638100480.

The previous prime is 21506524891. The next prime is 21506524927. The reversal of 21506524900 is 942560512.

It is a happy number.

It is a super-2 number, since 2×21506524900² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 234412 + ... + 312988.

It is an arithmetic number, because the mean of its divisors is an integer number (409234224).

Almost surely, 2^21506524900 is an apocalyptic number.

21506524900 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 21506524900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29464864128).

21506524900 is an abundant number, since it is smaller than the sum of its proper divisors (37423203356).

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

21506524900 is a wasteful number, since it uses less digits than its factorization.

21506524900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78638 (or 78631 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 34.

The spelling of 21506524900 in words is "twenty-one billion, five hundred six million, five hundred twenty-four thousand, nine hundred".