979217556521 has 4 divisors (see below), whose sum is σ = 979448453844. Its totient is φ = 978986659200.

The previous prime is 979217556391. The next prime is 979217556539. The reversal of 979217556521 is 125655712979.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 609718914025 + 369498642496 = 780845^2 + 607864^2 .

It is a cyclic number.

It is not a de Polignac number, because 979217556521 - 2¹⁰ = 979217555497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (979217586521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 115442300 + ... + 115450781.

It is an arithmetic number, because the mean of its divisors is an integer number (244862113461).

Almost surely, 2^979217556521 is an apocalyptic number.

It is an amenable number.

979217556521 is a deficient number, since it is larger than the sum of its proper divisors (230897323).

979217556521 is a wasteful number, since it uses less digits than its factorization.

979217556521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230897322.

The product of its digits is 11907000, while the sum is 59.

The spelling of 979217556521 in words is "nine hundred seventy-nine billion, two hundred seventeen million, five hundred fifty-six thousand, five hundred twenty-one".