991431169 has 15 divisors (see below), whose sum is σ = 1065200213. Its totient is φ = 922695048.

The previous prime is 991431167. The next prime is 991431179. The reversal of 991431169 is 961134199.

The square root of 991431169 is 31487.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 2 ways, for example, as 618168769 + 373262400 = 24863^2 + 19320^2 .

It is not a de Polignac number, because 991431169 - 2¹ = 991431167 is a prime.

It is a super-2 number, since 2×991431169² = 1965871525729413122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991431167) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 26795419 + ... + 26795455.

Almost surely, 2^991431169 is an apocalyptic number.

991431169 is the 31487-th square number.

991431169 is the 15744-th centered octagonal number.

It is an amenable number.

991431169 is a deficient number, since it is larger than the sum of its proper divisors (73769044).

991431169 is an frugal number, since it uses more digits than its factorization.

991431169 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 194 (or 60 counting only the distinct ones).

The product of its digits is 52488, while the sum is 43.

The cubic root of 991431169 is about 997.1355256211.

The spelling of 991431169 in words is "nine hundred ninety-one million, four hundred thirty-one thousand, one hundred sixty-nine".