991255037517 has 12 divisors (see below), whose sum is σ = 1444948730940. Its totient is φ = 654773969088.

The previous prime is 991255037471. The next prime is 991255037527. The reversal of 991255037517 is 715730552199.

991255037517 is a `hidden beast` number, since 9 + 9 + 1 + 2 + 550 + 3 + 75 + 17 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 709526567556 + 281728469961 = 842334^2 + 530781^2 .

It is not a de Polignac number, because 991255037517 - 2⁷ = 991255037389 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991255037527) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 505225848 + ... + 505227809.

It is an arithmetic number, because the mean of its divisors is an integer number (120412394245).

Almost surely, 2^991255037517 is an apocalyptic number.

It is an amenable number.

991255037517 is a deficient number, since it is larger than the sum of its proper divisors (453693693423).

991255037517 is a wasteful number, since it uses less digits than its factorization.

991255037517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1010453772 (or 1010453769 counting only the distinct ones).

The product of its (nonzero) digits is 2976750, while the sum is 54.

The spelling of 991255037517 in words is "nine hundred ninety-one billion, two hundred fifty-five million, thirty-seven thousand, five hundred seventeen".