78159581 has 2 divisors, whose sum is σ = 78159582. Its totient is φ = 78159580.

The previous prime is 78159527. The next prime is 78159583. The reversal of 78159581 is 18595187.

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., 71554681 + 6604900 = 8459^2 + 2570^2 .

It is a cyclic number.

It is not a de Polignac number, because 78159581 - 2⁶ = 78159517 is a prime.

It is a super-2 number, since 2×78159581² = 12217840204191122, which contains 22 as substring.

Together with 78159583, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78159583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39079790 + 39079791.

It is an arithmetic number, because the mean of its divisors is an integer number (39079791).

Almost surely, 2^78159581 is an apocalyptic number.

It is an amenable number.

78159581 is a deficient number, since it is larger than the sum of its proper divisors (1).

78159581 is an equidigital number, since it uses as much as digits as its factorization.

78159581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 100800, while the sum is 44.

The square root of 78159581 is about 8840.7907451766. The cubic root of 78159581 is about 427.5570522218.

The spelling of 78159581 in words is "seventy-eight million, one hundred fifty-nine thousand, five hundred eighty-one".