31816989 has 16 divisors (see below), whose sum is σ = 47937600. Its totient is φ = 20850768.

The previous prime is 31816987. The next prime is 31816997. The reversal of 31816989 is 98961813.

It is not a de Polignac number, because 31816989 - 2¹ = 31816987 is a prime.

It is a super-2 number, since 2×31816989² = 2024641578052242, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31816987) 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, 8394 + ... + 11579.

It is an arithmetic number, because the mean of its divisors is an integer number (2996100).

Almost surely, 2^31816989 is an apocalyptic number.

It is an amenable number.

31816989 is a deficient number, since it is larger than the sum of its proper divisors (16120611).

31816989 is a wasteful number, since it uses less digits than its factorization.

31816989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20041 (or 20035 counting only the distinct ones).

The product of its digits is 93312, while the sum is 45.

The square root of 31816989 is about 5640.6550151556. The cubic root of 31816989 is about 316.8738198899.

The spelling of 31816989 in words is "thirty-one million, eight hundred sixteen thousand, nine hundred eighty-nine".