31881861 has 12 divisors (see below), whose sum is σ = 50238240. Its totient is φ = 19322280.

The previous prime is 31881853. The next prime is 31881907. The reversal of 31881861 is 16818813.

It is not a de Polignac number, because 31881861 - 2³ = 31881853 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31881821) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 160921 + ... + 161118.

It is an arithmetic number, because the mean of its divisors is an integer number (4186520).

Almost surely, 2^31881861 is an apocalyptic number.

It is an amenable number.

31881861 is a deficient number, since it is larger than the sum of its proper divisors (18356379).

31881861 is a wasteful number, since it uses less digits than its factorization.

31881861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 322056 (or 322053 counting only the distinct ones).

The product of its digits is 9216, while the sum is 36.

The square root of 31881861 is about 5646.4024829975. The cubic root of 31881861 is about 317.0890328323.

The spelling of 31881861 in words is "thirty-one million, eight hundred eighty-one thousand, eight hundred sixty-one".