9991631 has 16 divisors (see below), whose sum is σ = 11793600. Its totient is φ = 8375808.

The previous prime is 9991603. The next prime is 9991649. The reversal of 9991631 is 1361999.

It is a cyclic number.

It is not a de Polignac number, because 9991631 - 2⁶ = 9991567 is a prime.

It is a super-2 number, since 2×9991631² = 199665380080322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9991691) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5630 + ... + 7188.

It is an arithmetic number, because the mean of its divisors is an integer number (737100).

Almost surely, 2^9991631 is an apocalyptic number.

9991631 is a deficient number, since it is larger than the sum of its proper divisors (1801969).

9991631 is a wasteful number, since it uses less digits than its factorization.

9991631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1618.

The product of its digits is 13122, while the sum is 38.

The square root of 9991631 is about 3160.9541281075. The cubic root of 9991631 is about 215.3833506827.

The spelling of 9991631 in words is "nine million, nine hundred ninety-one thousand, six hundred thirty-one".