31131321 has 12 divisors (see below), whose sum is σ = 44947728. Its totient is φ = 19157424.

The previous prime is 31131307. The next prime is 31131323. The reversal of 31131321 is 12313113.

It is not a de Polignac number, because 31131321 - 2⁶ = 31131257 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 31131321.

It is not an unprimeable number, because it can be changed into a prime (31131323) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 30195 + ... + 31208.

It is an arithmetic number, because the mean of its divisors is an integer number (3745644).

Almost surely, 2^31131321 is an apocalyptic number.

It is an amenable number.

31131321 is a deficient number, since it is larger than the sum of its proper divisors (13816407).

31131321 is a wasteful number, since it uses less digits than its factorization.

31131321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61432 (or 61419 counting only the distinct ones).

The product of its digits is 54, while the sum is 15.

The square root of 31131321 is about 5579.5448739122. The cubic root of 31131321 is about 314.5810201878.

Adding to 31131321 its reverse (12313113), we get a palindrome (43444434).

The spelling of 31131321 in words is "thirty-one million, one hundred thirty-one thousand, three hundred twenty-one".