31991999489 has 2 divisors, whose sum is σ = 31991999490. Its totient is φ = 31991999488.

The previous prime is 31991999483. The next prime is 31991999503. The reversal of 31991999489 is 98499919913.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 31575513025 + 416486464 = 177695^2 + 20408^2 .

It is a cyclic number.

It is not a de Polignac number, because 31991999489 - 2⁸ = 31991999233 is a prime.

It is a super-2 number, since 2×31991999489² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (31991999483) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15995999744 + 15995999745.

It is an arithmetic number, because the mean of its divisors is an integer number (15995999745).

Almost surely, 2^31991999489 is an apocalyptic number.

It is an amenable number.

31991999489 is a deficient number, since it is larger than the sum of its proper divisors (1).

31991999489 is an equidigital number, since it uses as much as digits as its factorization.

31991999489 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51018336, while the sum is 71.

The spelling of 31991999489 in words is "thirty-one billion, nine hundred ninety-one million, nine hundred ninety-nine thousand, four hundred eighty-nine".