251221551241 has 2 divisors, whose sum is σ = 251221551242. Its totient is φ = 251221551240.

The previous prime is 251221551239. The next prime is 251221551247. The reversal of 251221551241 is 142155122152.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 231818175625 + 19403375616 = 481475^2 + 139296^2 .

It is a cyclic number.

It is not a de Polignac number, because 251221551241 - 2¹ = 251221551239 is a prime.

It is a super-2 number, since 2×251221551241² (a number of 24 digits) contains 22 as substring.

Together with 251221551239, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (251221551247) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125610775620 + 125610775621.

It is an arithmetic number, because the mean of its divisors is an integer number (125610775621).

Almost surely, 2^251221551241 is an apocalyptic number.

It is an amenable number.

251221551241 is a deficient number, since it is larger than the sum of its proper divisors (1).

251221551241 is an equidigital number, since it uses as much as digits as its factorization.

251221551241 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8000, while the sum is 31.

Adding to 251221551241 its reverse (142155122152), we get a palindrome (393376673393).

The spelling of 251221551241 in words is "two hundred fifty-one billion, two hundred twenty-one million, five hundred fifty-one thousand, two hundred forty-one".