31155840 has 160 divisors (see below), whose sum is σ = 111448260. Its totient is φ = 8294400.

The previous prime is 31155833. The next prime is 31155841. The reversal of 31155840 is 4855113.

It can be written as a sum of positive squares in 2 ways, for example, as 30735936 + 419904 = 5544^2 + 648^2 .

It is a tau number, because it is divible by the number of its divisors (160).

It is a super-2 number, since 2×31155840² = 1941372732211200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31155841) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 51540 + ... + 52140.

Almost surely, 2^31155840 is an apocalyptic number.

31155840 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 31155840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (55724130).

31155840 is an abundant number, since it is smaller than the sum of its proper divisors (80292420).

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

31155840 is an equidigital number, since it uses as much as digits as its factorization.

31155840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 632 (or 611 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

The square root of 31155840 is about 5581.7416636745. The cubic root of 31155840 is about 314.6635864233.

The spelling of 31155840 in words is "thirty-one million, one hundred fifty-five thousand, eight hundred forty".