78138157 has 2 divisors, whose sum is σ = 78138158. Its totient is φ = 78138156.

The previous prime is 78138149. The next prime is 78138163. The reversal of 78138157 is 75183187.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59768361 + 18369796 = 7731^2 + 4286^2 .

It is an emirp because it is prime and its reverse (75183187) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78138157 - 2³ = 78138149 is a prime.

It is a super-2 number, since 2×78138157² = 12211143158713298, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78138187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39069078 + 39069079.

It is an arithmetic number, because the mean of its divisors is an integer number (39069079).

Almost surely, 2^78138157 is an apocalyptic number.

It is an amenable number.

78138157 is a deficient number, since it is larger than the sum of its proper divisors (1).

78138157 is an equidigital number, since it uses as much as digits as its factorization.

78138157 is an evil number, because the sum of its binary digits is even.

The product of its digits is 47040, while the sum is 40.

The square root of 78138157 is about 8839.5790058124. The cubic root of 78138157 is about 427.5179833526.

The spelling of 78138157 in words is "seventy-eight million, one hundred thirty-eight thousand, one hundred fifty-seven".