78639923 has 2 divisors, whose sum is σ = 78639924. Its totient is φ = 78639922.

The previous prime is 78639889. The next prime is 78639929. The reversal of 78639923 is 32993687.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 78639923 - 2⁶ = 78639859 is a prime.

It is not a weakly prime, because it can be changed into another prime (78639929) 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, 39319961 + 39319962.

It is an arithmetic number, because the mean of its divisors is an integer number (39319962).

Almost surely, 2^78639923 is an apocalyptic number.

78639923 is a deficient number, since it is larger than the sum of its proper divisors (1).

78639923 is an equidigital number, since it uses as much as digits as its factorization.

78639923 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 489888, while the sum is 47.

The square root of 78639923 is about 8867.9153694654. The cubic root of 78639923 is about 428.4311370916.

The spelling of 78639923 in words is "seventy-eight million, six hundred thirty-nine thousand, nine hundred twenty-three".