31820131 has 4 divisors (see below), whose sum is σ = 36365872. Its totient is φ = 27274392.

The previous prime is 31820123. The next prime is 31820153. The reversal of 31820131 is 13102813.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13102813 = 383 ⋅34211.

It is a cyclic number.

It is not a de Polignac number, because 31820131 - 2³ = 31820123 is a prime.

It is a super-2 number, since 2×31820131² = 2025041473714322, 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 = 31820099 and 31820108.

It is not an unprimeable number, because it can be changed into a prime (31820161) 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 3 ways as a sum of consecutive naturals, for example, 2272860 + ... + 2272873.

It is an arithmetic number, because the mean of its divisors is an integer number (9091468).

Almost surely, 2^31820131 is an apocalyptic number.

31820131 is a deficient number, since it is larger than the sum of its proper divisors (4545741).

31820131 is an equidigital number, since it uses as much as digits as its factorization.

31820131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4545740.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 31820131 is about 5640.9335220334. The cubic root of 31820131 is about 316.8842502166.

Adding to 31820131 its reverse (13102813), we get a palindrome (44922944).

It can be divided in two parts, 318 and 20131, that added together give a square (20449 = 143²).

The spelling of 31820131 in words is "thirty-one million, eight hundred twenty thousand, one hundred thirty-one".