31113720 has 224 divisors, whose sum is σ = 115683120. Its totient is φ = 7464960.

The previous prime is 31113713. The next prime is 31113749. The reversal of 31113720 is 2731113.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 31113693 and 31113702.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 320712 + ... + 320808.

Almost surely, 2^31113720 is an apocalyptic number.

31113720 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 31113720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (57841560).

31113720 is an abundant number, since it is smaller than the sum of its proper divisors (84569400).

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

31113720 is a wasteful number, since it uses less digits than its factorization.

31113720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137 (or 118 counting only the distinct ones).

The product of its (nonzero) digits is 126, while the sum is 18.

The square root of 31113720 is about 5577.9673717224. The cubic root of 31113720 is about 314.5217231607.

Adding to 31113720 its reverse (2731113), we get a palindrome (33844833).

The spelling of 31113720 in words is "thirty-one million, one hundred thirteen thousand, seven hundred twenty".