31131420 has 96 divisors (see below), whose sum is σ = 96380928. Its totient is φ = 7468032.

The previous prime is 31131407. The next prime is 31131421. The reversal of 31131420 is 2413113.

It is a super-2 number, since 2×31131420² = 1938330622432800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 31131420.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31131421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 22797 + ... + 24123.

It is an arithmetic number, because the mean of its divisors is an integer number (1003968).

Almost surely, 2^31131420 is an apocalyptic number.

31131420 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 31131420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48190464).

31131420 is an abundant number, since it is smaller than the sum of its proper divisors (65249508).

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

31131420 is a wasteful number, since it uses less digits than its factorization.

31131420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1379 (or 1377 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 15.

The square root of 31131420 is about 5579.5537455965. The cubic root of 31131420 is about 314.5813536514.

Adding to 31131420 its reverse (2413113), we get a palindrome (33544533).

The spelling of 31131420 in words is "thirty-one million, one hundred thirty-one thousand, four hundred twenty".