31813381 has 8 divisors (see below), whose sum is σ = 32361560. Its totient is φ = 31269888.

The previous prime is 31813357. The next prime is 31813387. The reversal of 31813381 is 18331813.

It can be written as a sum of positive squares in 4 ways, for example, as 6713281 + 25100100 = 2591^2 + 5010^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31813381 is a prime.

It is a super-2 number, since 2×31813381² = 2024182421302322, 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 (31813387) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14185 + ... + 16273.

It is an arithmetic number, because the mean of its divisors is an integer number (4045195).

Almost surely, 2^31813381 is an apocalyptic number.

It is an amenable number.

31813381 is a deficient number, since it is larger than the sum of its proper divisors (548179).

31813381 is a wasteful number, since it uses less digits than its factorization.

31813381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2343.

The product of its digits is 1728, while the sum is 28.

The square root of 31813381 is about 5640.3351850754. The cubic root of 31813381 is about 316.8618417612.

The spelling of 31813381 in words is "thirty-one million, eight hundred thirteen thousand, three hundred eighty-one".