31121557 has 2 divisors, whose sum is σ = 31121558. Its totient is φ = 31121556.

The previous prime is 31121527. The next prime is 31121561. The reversal of 31121557 is 75512113.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20304036 + 10817521 = 4506^2 + 3289^2 .

It is a cyclic number.

It is not a de Polignac number, because 31121557 - 2¹⁹ = 30597269 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31121527) 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 as a sum of consecutive naturals, namely, 15560778 + 15560779.

It is an arithmetic number, because the mean of its divisors is an integer number (15560779).

Almost surely, 2^31121557 is an apocalyptic number.

It is an amenable number.

31121557 is a deficient number, since it is larger than the sum of its proper divisors (1).

31121557 is an equidigital number, since it uses as much as digits as its factorization.

31121557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1050, while the sum is 25.

The square root of 31121557 is about 5578.6698235332. The cubic root of 31121557 is about 314.5481284444.

The spelling of 31121557 in words is "thirty-one million, one hundred twenty-one thousand, five hundred fifty-seven".