78138539 has 2 divisors, whose sum is σ = 78138540. Its totient is φ = 78138538.

The previous prime is 78138527. The next prime is 78138547. The reversal of 78138539 is 93583187.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (93583187) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78138539 - 2⁴ = 78138523 is a prime.

It is a super-2 number, since 2×78138539² = 12211262554109042, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 78138539.

It is not a weakly prime, because it can be changed into another prime (78138509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39069269 + 39069270.

It is an arithmetic number, because the mean of its divisors is an integer number (39069270).

Almost surely, 2^78138539 is an apocalyptic number.

78138539 is a deficient number, since it is larger than the sum of its proper divisors (1).

78138539 is an equidigital number, since it uses as much as digits as its factorization.

78138539 is an evil number, because the sum of its binary digits is even.

The product of its digits is 181440, while the sum is 44.

The square root of 78138539 is about 8839.6006131499. The cubic root of 78138539 is about 427.5186800314.

The spelling of 78138539 in words is "seventy-eight million, one hundred thirty-eight thousand, five hundred thirty-nine".