31116521 has 2 divisors, whose sum is σ = 31116522. Its totient is φ = 31116520.

The previous prime is 31116517. The next prime is 31116523. The reversal of 31116521 is 12561113.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 30647296 + 469225 = 5536^2 + 685^2 .

It is a cyclic number.

It is not a de Polignac number, because 31116521 - 2² = 31116517 is a prime.

Together with 31116523, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 31116493 and 31116502.

It is not a weakly prime, because it can be changed into another prime (31116523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15558260 + 15558261.

It is an arithmetic number, because the mean of its divisors is an integer number (15558261).

Almost surely, 2^31116521 is an apocalyptic number.

It is an amenable number.

31116521 is a deficient number, since it is larger than the sum of its proper divisors (1).

31116521 is an equidigital number, since it uses as much as digits as its factorization.

31116521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 180, while the sum is 20.

The square root of 31116521 is about 5578.2184431949. The cubic root of 31116521 is about 314.5311611076.

Adding to 31116521 its reverse (12561113), we get a palindrome (43677634).

The spelling of 31116521 in words is "thirty-one million, one hundred sixteen thousand, five hundred twenty-one".