251006556161 has 2 divisors, whose sum is σ = 251006556162. Its totient is φ = 251006556160.

The previous prime is 251006555957. The next prime is 251006556169. The reversal of 251006556161 is 161655600152.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 208432423936 + 42574132225 = 456544^2 + 206335^2 .

It is a cyclic number.

It is not a de Polignac number, because 251006556161 - 2³⁰ = 249932814337 is a prime.

It is not a weakly prime, because it can be changed into another prime (251006556169) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125503278080 + 125503278081.

It is an arithmetic number, because the mean of its divisors is an integer number (125503278081).

Almost surely, 2^251006556161 is an apocalyptic number.

It is an amenable number.

251006556161 is a deficient number, since it is larger than the sum of its proper divisors (1).

251006556161 is an equidigital number, since it uses as much as digits as its factorization.

251006556161 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 54000, while the sum is 38.

The spelling of 251006556161 in words is "two hundred fifty-one billion, six million, five hundred fifty-six thousand, one hundred sixty-one".