31393381 has 4 divisors (see below), whose sum is σ = 31530700. Its totient is φ = 31256064.

The previous prime is 31393379. The next prime is 31393387. The reversal of 31393381 is 18339313.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18339313 = 19 ⋅965227.

It can be written as a sum of positive squares in 2 ways, for example, as 16532356 + 14861025 = 4066^2 + 3855^2 .

It is a cyclic number.

It is not a de Polignac number, because 31393381 - 2¹ = 31393379 is a prime.

It is a super-2 number, since 2×31393381² = 1971088741222322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31393387) 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, 68316 + ... + 68773.

It is an arithmetic number, because the mean of its divisors is an integer number (7882675).

Almost surely, 2^31393381 is an apocalyptic number.

It is an amenable number.

31393381 is a deficient number, since it is larger than the sum of its proper divisors (137319).

31393381 is a wasteful number, since it uses less digits than its factorization.

31393381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137318.

The product of its digits is 5832, while the sum is 31.

The square root of 31393381 is about 5602.9796537200. The cubic root of 31393381 is about 315.4612575629.

The spelling of 31393381 in words is "thirty-one million, three hundred ninety-three thousand, three hundred eighty-one".