991947980 has 24 divisors (see below), whose sum is σ = 2096365488. Its totient is φ = 394250688.

The previous prime is 991947961. The next prime is 991947997. The reversal of 991947980 is 89749199.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 154814 + ... + 161093.

It is an arithmetic number, because the mean of its divisors is an integer number (87348562).

Almost surely, 2^991947980 is an apocalyptic number.

It is an amenable number.

991947980 is an abundant number, since it is smaller than the sum of its proper divisors (1104417508).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991947980 is a wasteful number, since it uses less digits than its factorization.

991947980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 316073 (or 316071 counting only the distinct ones).

The product of its (nonzero) digits is 1469664, while the sum is 56.

The square root of 991947980 is about 31495.2056668948. The cubic root of 991947980 is about 997.3087570420.

The spelling of 991947980 in words is "nine hundred ninety-one million, nine hundred forty-seven thousand, nine hundred eighty".