251312726221 has 2 divisors, whose sum is σ = 251312726222. Its totient is φ = 251312726220.

The previous prime is 251312726219. The next prime is 251312726239. The reversal of 251312726221 is 122627213152.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 233593389225 + 17719336996 = 483315^2 + 133114^2 .

It is a cyclic number.

It is not a de Polignac number, because 251312726221 - 2¹ = 251312726219 is a prime.

Together with 251312726219, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (251312720221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125656363110 + 125656363111.

It is an arithmetic number, because the mean of its divisors is an integer number (125656363111).

Almost surely, 2^251312726221 is an apocalyptic number.

It is an amenable number.

251312726221 is a deficient number, since it is larger than the sum of its proper divisors (1).

251312726221 is an equidigital number, since it uses as much as digits as its factorization.

251312726221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20160, while the sum is 34.

Adding to 251312726221 its reverse (122627213152), we get a palindrome (373939939373).

The spelling of 251312726221 in words is "two hundred fifty-one billion, three hundred twelve million, seven hundred twenty-six thousand, two hundred twenty-one".