31638420 has 216 divisors, whose sum is σ = 114135840. Its totient is φ = 7015680.

The previous prime is 31638389. The next prime is 31638427. The reversal of 31638420 is 2483613.

It is a happy number.

31638420 is a `hidden beast` number, since 3 + 1 + 638 + 4 + 20 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31638427) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1090966 + ... + 1090994.

Almost surely, 2^31638420 is an apocalyptic number.

31638420 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31638420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (57067920).

31638420 is an abundant number, since it is smaller than the sum of its proper divisors (82497420).

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

31638420 is a wasteful number, since it uses less digits than its factorization.

31638420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103 (or 69 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 31638420 is about 5624.8039965851. The cubic root of 31638420 is about 316.2799020818.

The spelling of 31638420 in words is "thirty-one million, six hundred thirty-eight thousand, four hundred twenty".