991978630 has 16 divisors (see below), whose sum is σ = 1810711584. Its totient is φ = 391202560.

The previous prime is 991978609. The next prime is 991978633. The reversal of 991978630 is 36879199.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991978633) 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, 697867 + ... + 699286.

It is an arithmetic number, because the mean of its divisors is an integer number (113169474).

Almost surely, 2^991978630 is an apocalyptic number.

991978630 is a deficient number, since it is larger than the sum of its proper divisors (818732954).

991978630 is a wasteful number, since it uses less digits than its factorization.

991978630 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1397231.

The product of its (nonzero) digits is 734832, while the sum is 52.

The square root of 991978630 is about 31495.6922451309. The cubic root of 991978630 is about 997.3190288168.

The spelling of 991978630 in words is "nine hundred ninety-one million, nine hundred seventy-eight thousand, six hundred thirty".