991880577 has 6 divisors (see below), whose sum is σ = 1432716402. Its totient is φ = 661253712.

The previous prime is 991880573. The next prime is 991880597. The reversal of 991880577 is 775088199.

It can be written as a sum of positive squares in only one way, i.e., 569824641 + 422055936 = 23871^2 + 20544^2 .

It is not a de Polignac number, because 991880577 - 2² = 991880573 is a prime.

It is not an unprimeable number, because it can be changed into a prime (991880573) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 55104468 + ... + 55104485.

It is an arithmetic number, because the mean of its divisors is an integer number (238786067).

Almost surely, 2^991880577 is an apocalyptic number.

It is an amenable number.

991880577 is a deficient number, since it is larger than the sum of its proper divisors (440835825).

991880577 is a wasteful number, since it uses less digits than its factorization.

991880577 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110208959 (or 110208956 counting only the distinct ones).

The product of its (nonzero) digits is 1270080, while the sum is 54.

The square root of 991880577 is about 31494.1355969647. The cubic root of 991880577 is about 997.2861674419.

The spelling of 991880577 in words is "nine hundred ninety-one million, eight hundred eighty thousand, five hundred seventy-seven".