918979921521 has 6 divisors (see below), whose sum is σ = 1327415442210. Its totient is φ = 612653281008.

The previous prime is 918979921513. The next prime is 918979921537. The reversal of 918979921521 is 125129979819.

918979921521 is a `hidden beast` number, since 9 + 1 + 89 + 7 + 9 + 9 + 21 + 521 = 666.

It can be written as a sum of positive squares in only one way, i.e., 917888544225 + 1091377296 = 958065^2 + 33036^2 .

It is not a de Polignac number, because 918979921521 - 2³ = 918979921513 is a prime.

It is not an unprimeable number, because it can be changed into a prime (918979921591) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 51054440076 + ... + 51054440093.

It is an arithmetic number, because the mean of its divisors is an integer number (221235907035).

Almost surely, 2^918979921521 is an apocalyptic number.

It is an amenable number.

918979921521 is a deficient number, since it is larger than the sum of its proper divisors (408435520689).

918979921521 is a wasteful number, since it uses less digits than its factorization.

918979921521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102108880175 (or 102108880172 counting only the distinct ones).

The product of its digits is 7348320, while the sum is 63.

The spelling of 918979921521 in words is "nine hundred eighteen billion, nine hundred seventy-nine million, nine hundred twenty-one thousand, five hundred twenty-one".