31808628 has 36 divisors (see below), whose sum is σ = 81242980. Its totient is φ = 10492416.

The previous prime is 31808627. The next prime is 31808629. The reversal of 31808628 is 82680813.

It is an interprime number because it is at equal distance from previous prime (31808627) and next prime (31808629).

It can be written as a sum of positive squares in 2 ways, for example, as 8363664 + 23444964 = 2892^2 + 4842^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 31808592 and 31808601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31808627) 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, 1063 + ... + 8046.

Almost surely, 2^31808628 is an apocalyptic number.

It is an amenable number.

31808628 is an abundant number, since it is smaller than the sum of its proper divisors (49434352).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31808628 is a wasteful number, since it uses less digits than its factorization.

31808628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9216 (or 9211 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 36.

The square root of 31808628 is about 5639.9138291290. The cubic root of 31808628 is about 316.8460609871.

The spelling of 31808628 in words is "thirty-one million, eight hundred eight thousand, six hundred twenty-eight".