7721157031920 has 800 divisors, whose sum is σ = 29204073676800. Its totient is φ = 1883051089920.

The previous prime is 7721157031909. The next prime is 7721157031949. The reversal of 7721157031920 is 291307511277.

7721157031920 is a `hidden beast` number, since 7 + 7 + 21 + 1 + 570 + 31 + 9 + 20 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 942635025 + ... + 942643215.

It is an arithmetic number, because the mean of its divisors is an integer number (36505092096).

Almost surely, 2^{7721157031920} 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 7721157031920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14602036838400).

7721157031920 is an abundant number, since it is smaller than the sum of its proper divisors (21482916644880).

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

7721157031920 is a wasteful number, since it uses less digits than its factorization.

7721157031920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8475 (or 8460 counting only the distinct ones).

The product of its (nonzero) digits is 185220, while the sum is 45.

The spelling of 7721157031920 in words is "seven trillion, seven hundred twenty-one billion, one hundred fifty-seven million, thirty-one thousand, nine hundred twenty".