991178025 has 12 divisors (see below), whose sum is σ = 1638747792. Its totient is φ = 528628240.

The previous prime is 991178017. The next prime is 991178053. The reversal of 991178025 is 520871199.

It is not a de Polignac number, because 991178025 - 2³ = 991178017 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6607779 + ... + 6607928.

It is an arithmetic number, because the mean of its divisors is an integer number (136562316).

Almost surely, 2^991178025 is an apocalyptic number.

It is an amenable number.

991178025 is a deficient number, since it is larger than the sum of its proper divisors (647569767).

991178025 is a wasteful number, since it uses less digits than its factorization.

991178025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13215720 (or 13215715 counting only the distinct ones).

The product of its (nonzero) digits is 45360, while the sum is 42.

The square root of 991178025 is about 31482.9799256678. The cubic root of 991178025 is about 997.0506515622.

The spelling of 991178025 in words is "nine hundred ninety-one million, one hundred seventy-eight thousand, twenty-five".