78140639 has 2 divisors, whose sum is σ = 78140640. Its totient is φ = 78140638.

The previous prime is 78140617. The next prime is 78140651. The reversal of 78140639 is 93604187.

It is a strong prime.

It is an emirp because it is prime and its reverse (93604187) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78140639 - 2¹⁶ = 78075103 is a prime.

It is a super-2 number, since 2×78140639² = 12211918926656642, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78140609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39070319 + 39070320.

It is an arithmetic number, because the mean of its divisors is an integer number (39070320).

Almost surely, 2^78140639 is an apocalyptic number.

78140639 is a deficient number, since it is larger than the sum of its proper divisors (1).

78140639 is an equidigital number, since it uses as much as digits as its factorization.

78140639 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36288, while the sum is 38.

The square root of 78140639 is about 8839.7193959989. The cubic root of 78140639 is about 427.5225099008.

The spelling of 78140639 in words is "seventy-eight million, one hundred forty thousand, six hundred thirty-nine".