21931689600 has 480 divisors, whose sum is σ = 81540138240. Its totient is φ = 5804697600.

The previous prime is 21931689469. The next prime is 21931689601. The reversal of 21931689600 is 698613912.

It is a happy number.

21931689600 is a `hidden beast` number, since 2 + 1 + 9 + 31 + 6 + 8 + 9 + 600 = 666.

It is a tau number, because it is divible by the number of its divisors (480).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (21931689601) by changing a digit.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 49506979 + ... + 49507421.

It is an arithmetic number, because the mean of its divisors is an integer number (169875288).

Almost surely, 2^21931689600 is an apocalyptic number.

21931689600 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 21931689600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40770069120).

21931689600 is an abundant number, since it is smaller than the sum of its proper divisors (59608448640).

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

21931689600 is a wasteful number, since it uses less digits than its factorization.

21931689600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 670 (or 644 counting only the distinct ones).

The product of its (nonzero) digits is 139968, while the sum is 45.

The spelling of 21931689600 in words is "twenty-one billion, nine hundred thirty-one million, six hundred eighty-nine thousand, six hundred".