21256066631220 has 192 divisors, whose sum is σ = 63562128005376. Its totient is φ = 5288871976960.

The previous prime is 21256066631207. The next prime is 21256066631231. The reversal of 21256066631220 is 2213666065212.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 135278542 + ... + 135435578.

It is an arithmetic number, because the mean of its divisors is an integer number (331052750028).

Almost surely, 2^{21256066631220} is an apocalyptic number.

21256066631220 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 21256066631220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31781064002688).

21256066631220 is an abundant number, since it is smaller than the sum of its proper divisors (42306061374156).

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

21256066631220 is a wasteful number, since it uses less digits than its factorization.

21256066631220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 158210 (or 158208 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 42.

The spelling of 21256066631220 in words is "twenty-one trillion, two hundred fifty-six billion, sixty-six million, six hundred thirty-one thousand, two hundred twenty".