251678891 has 2 divisors, whose sum is σ = 251678892. Its totient is φ = 251678890.

The previous prime is 251678887. The next prime is 251678893. The reversal of 251678891 is 198876152.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 251678891 - 2² = 251678887 is a prime.

Together with 251678893, 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 (251678893) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125839445 + 125839446.

It is an arithmetic number, because the mean of its divisors is an integer number (125839446).

Almost surely, 2^251678891 is an apocalyptic number.

251678891 is a deficient number, since it is larger than the sum of its proper divisors (1).

251678891 is an equidigital number, since it uses as much as digits as its factorization.

251678891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 241920, while the sum is 47.

The square root of 251678891 is about 15864.3906595873. The cubic root of 251678891 is about 631.3675600283.

The spelling of 251678891 in words is "two hundred fifty-one million, six hundred seventy-eight thousand, eight hundred ninety-one".