31221128935897 has 2 divisors, whose sum is σ = 31221128935898. Its totient is φ = 31221128935896.

The previous prime is 31221128935883. The next prime is 31221128935921. The reversal of 31221128935897 is 79853982112213.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27423194464656 + 3797934471241 = 5236716^2 + 1948829^2 .

It is a cyclic number.

It is not a de Polignac number, because 31221128935897 - 2¹⁹ = 31221128411609 is a prime.

It is not a weakly prime, because it can be changed into another prime (31221128935837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15610564467948 + 15610564467949.

It is an arithmetic number, because the mean of its divisors is an integer number (15610564467949).

Almost surely, 2^{31221128935897} is an apocalyptic number.

It is an amenable number.

31221128935897 is a deficient number, since it is larger than the sum of its proper divisors (1).

31221128935897 is an equidigital number, since it uses as much as digits as its factorization.

31221128935897 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13063680, while the sum is 61.

The spelling of 31221128935897 in words is "thirty-one trillion, two hundred twenty-one billion, one hundred twenty-eight million, nine hundred thirty-five thousand, eight hundred ninety-seven".