991297919979 has 8 divisors (see below), whose sum is σ = 1468589511120. Its totient is φ = 660865279968.

The previous prime is 991297919959. The next prime is 991297920047. The reversal of 991297919979 is 979919792199.

It is a happy number.

991297919979 is a `hidden beast` number, since 9 + 91 + 297 + 91 + 99 + 79 = 666.

It is not a de Polignac number, because 991297919979 - 2⁵ = 991297919947 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 991297919898 and 991297919907.

It is not an unprimeable number, because it can be changed into a prime (991297919959) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18357368862 + ... + 18357368915.

It is an arithmetic number, because the mean of its divisors is an integer number (183573688890).

Almost surely, 2^991297919979 is an apocalyptic number.

991297919979 is a deficient number, since it is larger than the sum of its proper divisors (477291591141).

991297919979 is a wasteful number, since it uses less digits than its factorization.

991297919979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36714737786 (or 36714737780 counting only the distinct ones).

The product of its digits is 468730962, while the sum is 81.

It can be divided in two parts, 99129 and 7919979, that added together give a palindrome (8019108).

The spelling of 991297919979 in words is "nine hundred ninety-one billion, two hundred ninety-seven million, nine hundred nineteen thousand, nine hundred seventy-nine".