31261999889 has 2 divisors, whose sum is σ = 31261999890. Its totient is φ = 31261999888.

The previous prime is 31261999877. The next prime is 31261999891. The reversal of 31261999889 is 98899916213.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16895580289 + 14366419600 = 129983^2 + 119860^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31261999889 is a prime.

Together with 31261999891, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (31261999819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15630999944 + 15630999945.

It is an arithmetic number, because the mean of its divisors is an integer number (15630999945).

Almost surely, 2^31261999889 is an apocalyptic number.

It is an amenable number.

31261999889 is a deficient number, since it is larger than the sum of its proper divisors (1).

31261999889 is an equidigital number, since it uses as much as digits as its factorization.

31261999889 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15116544, while the sum is 65.

The spelling of 31261999889 in words is "thirty-one billion, two hundred sixty-one million, nine hundred ninety-nine thousand, eight hundred eighty-nine".