31281999997 has 2 divisors, whose sum is σ = 31281999998. Its totient is φ = 31281999996.

The previous prime is 31281999977. The next prime is 31282000019. The reversal of 31281999997 is 79999918213.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19571730201 + 11710269796 = 139899^2 + 108214^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31281999997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31281999967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15640999998 + 15640999999.

It is an arithmetic number, because the mean of its divisors is an integer number (15640999999).

Almost surely, 2^31281999997 is an apocalyptic number.

It is an amenable number.

31281999997 is a deficient number, since it is larger than the sum of its proper divisors (1).

31281999997 is an equidigital number, since it uses as much as digits as its factorization.

31281999997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19840464, while the sum is 67.

The spelling of 31281999997 in words is "thirty-one billion, two hundred eighty-one million, nine hundred ninety-nine thousand, nine hundred ninety-seven".