78313561 has 2 divisors, whose sum is σ = 78313562. Its totient is φ = 78313560.

The previous prime is 78313541. The next prime is 78313589. The reversal of 78313561 is 16531387.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 63297936 + 15015625 = 7956^2 + 3875^2 .

It is a cyclic number.

It is not a de Polignac number, because 78313561 - 2⁹ = 78313049 is a prime.

It is a super-2 number, since 2×78313561² = 12266027673001442, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78313511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39156780 + 39156781.

It is an arithmetic number, because the mean of its divisors is an integer number (39156781).

Almost surely, 2^78313561 is an apocalyptic number.

It is an amenable number.

78313561 is a deficient number, since it is larger than the sum of its proper divisors (1).

78313561 is an equidigital number, since it uses as much as digits as its factorization.

78313561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15120, while the sum is 34.

The square root of 78313561 is about 8849.4949573408. The cubic root of 78313561 is about 427.8376407644.

The spelling of 78313561 in words is "seventy-eight million, three hundred thirteen thousand, five hundred sixty-one".