78253691 has 2 divisors, whose sum is σ = 78253692. Its totient is φ = 78253690.

The previous prime is 78253663. The next prime is 78253699. The reversal of 78253691 is 19635287.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 78253691 - 2⁶ = 78253627 is a prime.

It is a super-3 number, since 3×78253691³ (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (78253699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39126845 + 39126846.

It is an arithmetic number, because the mean of its divisors is an integer number (39126846).

Almost surely, 2^78253691 is an apocalyptic number.

78253691 is a deficient number, since it is larger than the sum of its proper divisors (1).

78253691 is an equidigital number, since it uses as much as digits as its factorization.

78253691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 41.

The square root of 78253691 is about 8846.1116316718. Note that the first 3 decimals coincide. The cubic root of 78253691 is about 427.7285869838.

The spelling of 78253691 in words is "seventy-eight million, two hundred fifty-three thousand, six hundred ninety-one".