78631639 has 2 divisors, whose sum is σ = 78631640. Its totient is φ = 78631638.

The previous prime is 78631591. The next prime is 78631661. The reversal of 78631639 is 93613687.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 78631639 - 2¹¹ = 78629591 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 78631595 and 78631604.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78631699) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39315819 + 39315820.

It is an arithmetic number, because the mean of its divisors is an integer number (39315820).

Almost surely, 2^78631639 is an apocalyptic number.

78631639 is a deficient number, since it is larger than the sum of its proper divisors (1).

78631639 is an equidigital number, since it uses as much as digits as its factorization.

78631639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 163296, while the sum is 43.

The square root of 78631639 is about 8867.4482800860. The cubic root of 78631639 is about 428.4160927900.

The spelling of 78631639 in words is "seventy-eight million, six hundred thirty-one thousand, six hundred thirty-nine".