21256265479680 has 1920 divisors, whose sum is σ = 100862169408000. Its totient is φ = 4184279285760.

The previous prime is 21256265479679. The next prime is 21256265479703. The reversal of 21256265479680 is 8697456265212.

21256265479680 is a `hidden beast` number, since 2 + 1 + 2 + 5 + 6 + 2 + 6 + 547 + 9 + 6 + 80 = 666.

It is a tau number, because it is divible by the number of its divisors (1920).

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 707842906 + ... + 707872934.

It is an arithmetic number, because the mean of its divisors is an integer number (52532379900).

Almost surely, 2^{21256265479680} is an apocalyptic number.

21256265479680 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 21256265479680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (50431084704000).

21256265479680 is an abundant number, since it is smaller than the sum of its proper divisors (79605903928320).

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

21256265479680 is a wasteful number, since it uses less digits than its factorization.

21256265479680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30105 (or 30076 counting only the distinct ones).

The product of its (nonzero) digits is 87091200, while the sum is 63.

The spelling of 21256265479680 in words is "twenty-one trillion, two hundred fifty-six billion, two hundred sixty-five million, four hundred seventy-nine thousand, six hundred eighty".