68991257 has 2 divisors, whose sum is σ = 68991258. Its totient is φ = 68991256.

The previous prime is 68991239. The next prime is 68991259. The reversal of 68991257 is 75219986.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 37810201 + 31181056 = 6149^2 + 5584^2 .

It is a cyclic number.

It is not a de Polignac number, because 68991257 - 2⁶ = 68991193 is a prime.

Together with 68991259, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (68991259) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 34495628 + 34495629.

It is an arithmetic number, because the mean of its divisors is an integer number (34495629).

Almost surely, 2^68991257 is an apocalyptic number.

It is an amenable number.

68991257 is a deficient number, since it is larger than the sum of its proper divisors (1).

68991257 is an equidigital number, since it uses as much as digits as its factorization.

68991257 is an evil number, because the sum of its binary digits is even.

The product of its digits is 272160, while the sum is 47.

The square root of 68991257 is about 8306.0975794894. The cubic root of 68991257 is about 410.1392685714.

The spelling of 68991257 in words is "sixty-eight million, nine hundred ninety-one thousand, two hundred fifty-seven".