21305664120 has 256 divisors, whose sum is σ = 74855975040. Its totient is φ = 4802347008.

The previous prime is 21305664113. The next prime is 21305664131. The reversal of 21305664120 is 2146650312.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 970384 + ... + 992096.

Almost surely, 2^21305664120 is an apocalyptic number.

21305664120 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 21305664120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37427987520).

21305664120 is an abundant number, since it is smaller than the sum of its proper divisors (53550310920).

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

21305664120 is a wasteful number, since it uses less digits than its factorization.

21305664120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21794 (or 21790 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

The spelling of 21305664120 in words is "twenty-one billion, three hundred five million, six hundred sixty-four thousand, one hundred twenty".