991973577 has 32 divisors (see below), whose sum is σ = 1525888000. Its totient is φ = 561504960.

The previous prime is 991973561. The next prime is 991973597. The reversal of 991973577 is 775379199.

It is not a de Polignac number, because 991973577 - 2⁴ = 991973561 is a prime.

It is not an unprimeable number, because it can be changed into a prime (991973597) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1896438 + ... + 1896960.

It is an arithmetic number, because the mean of its divisors is an integer number (47684000).

Almost surely, 2^991973577 is an apocalyptic number.

It is an amenable number.

991973577 is a deficient number, since it is larger than the sum of its proper divisors (533914423).

991973577 is a wasteful number, since it uses less digits than its factorization.

991973577 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1213.

The product of its digits is 3750705, while the sum is 57.

The square root of 991973577 is about 31495.6120277095. The cubic root of 991973577 is about 997.3173354128.

The spelling of 991973577 in words is "nine hundred ninety-one million, nine hundred seventy-three thousand, five hundred seventy-seven".