251528116621 has 2 divisors, whose sum is σ = 251528116622. Its totient is φ = 251528116620.

The previous prime is 251528116607. The next prime is 251528116661. The reversal of 251528116621 is 126611825152.

It is an a-pointer prime, because the next prime (251528116661) can be obtained adding 251528116621 to its sum of digits (40).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 247481375625 + 4046740996 = 497475^2 + 63614^2 .

It is a cyclic number.

It is not a de Polignac number, because 251528116621 - 2⁵ = 251528116589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (251528116661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125764058310 + 125764058311.

It is an arithmetic number, because the mean of its divisors is an integer number (125764058311).

Almost surely, 2^251528116621 is an apocalyptic number.

It is an amenable number.

251528116621 is a deficient number, since it is larger than the sum of its proper divisors (1).

251528116621 is an equidigital number, since it uses as much as digits as its factorization.

251528116621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 57600, while the sum is 40.

The spelling of 251528116621 in words is "two hundred fifty-one billion, five hundred twenty-eight million, one hundred sixteen thousand, six hundred twenty-one".