251221679 has 2 divisors, whose sum is σ = 251221680. Its totient is φ = 251221678.

The previous prime is 251221673. The next prime is 251221681. The reversal of 251221679 is 976122152.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-251221679 is a prime.

It is a super-2 number, since 2×251221679² = 126224663999158082, which contains 22 as substring.

Together with 251221681, 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 (251221673) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125610839 + 125610840.

It is an arithmetic number, because the mean of its divisors is an integer number (125610840).

Almost surely, 2^251221679 is an apocalyptic number.

251221679 is a deficient number, since it is larger than the sum of its proper divisors (1).

251221679 is an equidigital number, since it uses as much as digits as its factorization.

251221679 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15120, while the sum is 35.

The square root of 251221679 is about 15849.9741009252. The cubic root of 251221679 is about 630.9850040346.

The spelling of 251221679 in words is "two hundred fifty-one million, two hundred twenty-one thousand, six hundred seventy-nine".