21979431036990 has 256 divisors, whose sum is σ = 68325435463680. Its totient is φ = 4923918720000.

The previous prime is 21979431036973. The next prime is 21979431037007. The reversal of 21979431036990 is 9963013497912.

21979431036990 is a `hidden beast` number, since 2 + 1 + 97 + 94 + 3 + 10 + 369 + 90 = 666.

It is an interprime number because it is at equal distance from previous prime (21979431036973) and next prime (21979431037007).

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 127 ways as a sum of consecutive naturals, for example, 32057265 + ... + 32735715.

It is an arithmetic number, because the mean of its divisors is an integer number (266896232280).

Almost surely, 2^{21979431036990} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21979431036990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34162717731840).

21979431036990 is an abundant number, since it is smaller than the sum of its proper divisors (46346004426690).

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

21979431036990 is a wasteful number, since it uses less digits than its factorization.

21979431036990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 678816 (or 678810 counting only the distinct ones).

The product of its (nonzero) digits is 19840464, while the sum is 63.

The spelling of 21979431036990 in words is "twenty-one trillion, nine hundred seventy-nine billion, four hundred thirty-one million, thirty-six thousand, nine hundred ninety".