31638540 has 48 divisors (see below), whose sum is σ = 90655488. Its totient is φ = 8240064.

The previous prime is 31638533. The next prime is 31638557. The reversal of 31638540 is 4583613.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 31638498 and 31638507.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3552 + ... + 8711.

It is an arithmetic number, because the mean of its divisors is an integer number (1888656).

Almost surely, 2^31638540 is an apocalyptic number.

31638540 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

31638540 is an abundant number, since it is smaller than the sum of its proper divisors (59016948).

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

31638540 is a wasteful number, since it uses less digits than its factorization.

31638540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12318 (or 12316 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 31638540 is about 5624.8146636134. The cubic root of 31638540 is about 316.2803019494.

The spelling of 31638540 in words is "thirty-one million, six hundred thirty-eight thousand, five hundred forty".