991900977 has 4 divisors (see below), whose sum is σ = 1322534640. Its totient is φ = 661267316.

The previous prime is 991900939. The next prime is 991900993. The reversal of 991900977 is 779009199.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 991900977 - 2¹⁵ = 991868209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (991900937) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 165316827 + ... + 165316832.

It is an arithmetic number, because the mean of its divisors is an integer number (330633660).

Almost surely, 2^991900977 is an apocalyptic number.

It is an amenable number.

991900977 is a deficient number, since it is larger than the sum of its proper divisors (330633663).

991900977 is a wasteful number, since it uses less digits than its factorization.

991900977 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 330633662.

The product of its (nonzero) digits is 321489, while the sum is 51.

The square root of 991900977 is about 31494.4594651186. The cubic root of 991900977 is about 997.2930044539.

The spelling of 991900977 in words is "nine hundred ninety-one million, nine hundred thousand, nine hundred seventy-seven".