78781631 has 2 divisors, whose sum is σ = 78781632. Its totient is φ = 78781630.

The previous prime is 78781613. The next prime is 78781687. The reversal of 78781631 is 13618787.

Together with previous prime (78781613) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 78781631 - 2⁶ = 78781567 is a prime.

It is a super-2 number, since 2×78781631² = 12413090766040322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78781231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39390815 + 39390816.

It is an arithmetic number, because the mean of its divisors is an integer number (39390816).

Almost surely, 2^78781631 is an apocalyptic number.

78781631 is a deficient number, since it is larger than the sum of its proper divisors (1).

78781631 is an equidigital number, since it uses as much as digits as its factorization.

78781631 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 56448, while the sum is 41.

The square root of 78781631 is about 8875.9017006724. The cubic root of 78781631 is about 428.6883249010.

The spelling of 78781631 in words is "seventy-eight million, seven hundred eighty-one thousand, six hundred thirty-one".