31381121 has 2 divisors, whose sum is σ = 31381122. Its totient is φ = 31381120.

The previous prime is 31381087. The next prime is 31381127. The reversal of 31381121 is 12118313.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 28944400 + 2436721 = 5380^2 + 1561^2 .

It is an emirp because it is prime and its reverse (12118313) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31381121 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 31381093 and 31381102.

It is not a weakly prime, because it can be changed into another prime (31381127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15690560 + 15690561.

It is an arithmetic number, because the mean of its divisors is an integer number (15690561).

Almost surely, 2^31381121 is an apocalyptic number.

It is an amenable number.

31381121 is a deficient number, since it is larger than the sum of its proper divisors (1).

31381121 is an equidigital number, since it uses as much as digits as its factorization.

31381121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 144, while the sum is 20.

The square root of 31381121 is about 5601.8854861555. The cubic root of 31381121 is about 315.4201867122.

Adding to 31381121 its reverse (12118313), we get a palindrome (43499434).

The spelling of 31381121 in words is "thirty-one million, three hundred eighty-one thousand, one hundred twenty-one".