7920881557821 has 32 divisors (see below), whose sum is σ = 11874916224000. Its totient is φ = 5217547382784.

The previous prime is 7920881557819. The next prime is 7920881557871. The reversal of 7920881557821 is 1287551880297.

7920881557821 is a `hidden beast` number, since 7 + 9 + 20 + 8 + 8 + 15 + 578 + 21 = 666.

It is not a de Polignac number, because 7920881557821 - 2¹ = 7920881557819 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7920881557871) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2216116 + ... + 4555538.

It is an arithmetic number, because the mean of its divisors is an integer number (371091132000).

Almost surely, 2^{7920881557821} is an apocalyptic number.

It is an amenable number.

7920881557821 is a deficient number, since it is larger than the sum of its proper divisors (3954034666179).

7920881557821 is a wasteful number, since it uses less digits than its factorization.

7920881557821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2340930 (or 2340924 counting only the distinct ones).

The product of its (nonzero) digits is 22579200, while the sum is 63.

The spelling of 7920881557821 in words is "seven trillion, nine hundred twenty billion, eight hundred eighty-one million, five hundred fifty-seven thousand, eight hundred twenty-one".