21891320726912 has 768 divisors, whose sum is σ = 59524048281600. Its totient is φ = 7924602470400.

The previous prime is 21891320726861. The next prime is 21891320726929. The reversal of 21891320726912 is 21962702319812.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 5174027837 + ... + 5174032067.

It is an arithmetic number, because the mean of its divisors is an integer number (77505271200).

Almost surely, 2^{21891320726912} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21891320726912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29762024140800).

21891320726912 is an abundant number, since it is smaller than the sum of its proper divisors (37632727554688).

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

21891320726912 is a wasteful number, since it uses less digits than its factorization.

21891320726912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4415 (or 4396 counting only the distinct ones).

The product of its (nonzero) digits is 1306368, while the sum is 53.

The spelling of 21891320726912 in words is "twenty-one trillion, eight hundred ninety-one billion, three hundred twenty million, seven hundred twenty-six thousand, nine hundred twelve".