31312321 has 4 divisors (see below), whose sum is σ = 31599700. Its totient is φ = 31024944.

The previous prime is 31312301. The next prime is 31312327. The reversal of 31312321 is 12321313.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12321313 = 193 ⋅63841.

It can be written as a sum of positive squares in 2 ways, for example, as 14592400 + 16719921 = 3820^2 + 4089^2 .

It is a cyclic number.

It is not a de Polignac number, because 31312321 - 2²³ = 22923713 is a prime.

It is a super-2 number, since 2×31312321² = 1960922892814082, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31312295 and 31312304.

It is not an unprimeable number, because it can be changed into a prime (31312327) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 143526 + ... + 143743.

It is an arithmetic number, because the mean of its divisors is an integer number (7899925).

Almost surely, 2^31312321 is an apocalyptic number.

It is an amenable number.

31312321 is a deficient number, since it is larger than the sum of its proper divisors (287379).

31312321 is a wasteful number, since it uses less digits than its factorization.

31312321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 287378.

The product of its digits is 108, while the sum is 16.

The square root of 31312321 is about 5595.7413271165. The cubic root of 31312321 is about 315.1895088766.

Adding to 31312321 its reverse (12321313), we get a palindrome (43633634).

The spelling of 31312321 in words is "thirty-one million, three hundred twelve thousand, three hundred twenty-one".