31187961 has 24 divisors (see below), whose sum is σ = 52540800. Its totient is φ = 17819928.

The previous prime is 31187951. The next prime is 31187971. The reversal of 31187961 is 16978113.

It is an interprime number because it is at equal distance from previous prime (31187951) and next prime (31187971).

It is not a de Polignac number, because 31187961 - 2¹⁴ = 31171577 is a prime.

It is a super-2 number, since 2×31187961² = 1945377822675042, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (31187941) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1965 + ... + 8138.

It is an arithmetic number, because the mean of its divisors is an integer number (2189200).

Almost surely, 2^31187961 is an apocalyptic number.

It is an amenable number.

31187961 is a deficient number, since it is larger than the sum of its proper divisors (21352839).

31187961 is a wasteful number, since it uses less digits than its factorization.

31187961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10130 (or 10113 counting only the distinct ones).

The product of its digits is 9072, while the sum is 36.

The square root of 31187961 is about 5584.6182501582. The cubic root of 31187961 is about 314.7716864090.

The spelling of 31187961 in words is "thirty-one million, one hundred eighty-seven thousand, nine hundred sixty-one".