31499991 has 6 divisors (see below), whose sum is σ = 45500000. Its totient is φ = 20999988.

The previous prime is 31499989. The next prime is 31500017. The reversal of 31499991 is 19999413.

It is not a de Polignac number, because 31499991 - 2¹ = 31499989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31499921) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1749991 + ... + 1750008.

Almost surely, 2^31499991 is an apocalyptic number.

31499991 is a deficient number, since it is larger than the sum of its proper divisors (14000009).

31499991 is a wasteful number, since it uses less digits than its factorization.

31499991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3500005 (or 3500002 counting only the distinct ones).

The product of its digits is 78732, while the sum is 45.

The square root of 31499991 is about 5612.4852783771. The cubic root of 31499991 is about 315.8179498049.

The spelling of 31499991 in words is "thirty-one million, four hundred ninety-nine thousand, nine hundred ninety-one".