991554977047 has 4 divisors (see below), whose sum is σ = 1005520540176. Its totient is φ = 977589413920.

The previous prime is 991554977041. The next prime is 991554977087. The reversal of 991554977047 is 740779455199.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 991554977047 - 2²⁷ = 991420759319 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991554977041) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6982781458 + ... + 6982781599.

It is an arithmetic number, because the mean of its divisors is an integer number (251380135044).

Almost surely, 2^991554977047 is an apocalyptic number.

991554977047 is a deficient number, since it is larger than the sum of its proper divisors (13965563129).

991554977047 is a wasteful number, since it uses less digits than its factorization.

991554977047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13965563128.

The product of its (nonzero) digits is 100018800, while the sum is 67.

The spelling of 991554977047 in words is "nine hundred ninety-one billion, five hundred fifty-four million, nine hundred seventy-seven thousand, forty-seven".