31291121 has 6 divisors (see below), whose sum is σ = 32334066. Its totient is φ = 30280800.

The previous prime is 31291111. The next prime is 31291123. The reversal of 31291121 is 12119213.

It can be written as a sum of positive squares in only one way, i.e., 29430625 + 1860496 = 5425^2 + 1364^2 .

It is a de Polignac number, because none of the positive numbers 2^k-31291121 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31291093 and 31291102.

It is not an unprimeable number, because it can be changed into a prime (31291123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 15320 + ... + 17241.

It is an arithmetic number, because the mean of its divisors is an integer number (5389011).

Almost surely, 2^31291121 is an apocalyptic number.

31291121 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

It is an amenable number.

31291121 is a deficient number, since it is larger than the sum of its proper divisors (1042945).

31291121 is an equidigital number, since it uses as much as digits as its factorization.

31291121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32623 (or 32592 counting only the distinct ones).

The product of its digits is 108, while the sum is 20.

The square root of 31291121 is about 5593.8467086612. The cubic root of 31291121 is about 315.1183598213.

The spelling of 31291121 in words is "thirty-one million, two hundred ninety-one thousand, one hundred twenty-one".