251426125661 has 4 divisors (see below), whose sum is σ = 252404437692. Its totient is φ = 250447813632.

The previous prime is 251426125609. The next prime is 251426125669. The reversal of 251426125661 is 166521624152.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 215476069636 + 35950056025 = 464194^2 + 189605^2 .

It is a cyclic number.

It is not a de Polignac number, because 251426125661 - 2⁶ = 251426125597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251426125669) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 489155630 + ... + 489156143.

It is an arithmetic number, because the mean of its divisors is an integer number (63101109423).

Almost surely, 2^251426125661 is an apocalyptic number.

It is an amenable number.

251426125661 is a deficient number, since it is larger than the sum of its proper divisors (978312031).

251426125661 is an equidigital number, since it uses as much as digits as its factorization.

251426125661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 978312030.

The product of its digits is 172800, while the sum is 41.

The spelling of 251426125661 in words is "two hundred fifty-one billion, four hundred twenty-six million, one hundred twenty-five thousand, six hundred sixty-one".