251912161 has 4 divisors (see below), whose sum is σ = 255672112. Its totient is φ = 248152212.

The previous prime is 251912153. The next prime is 251912191. The reversal of 251912161 is 161219152.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 251912161 - 2³ = 251912153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (251912131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1879875 + ... + 1880008.

It is an arithmetic number, because the mean of its divisors is an integer number (63918028).

Almost surely, 2^251912161 is an apocalyptic number.

It is an amenable number.

251912161 is a deficient number, since it is larger than the sum of its proper divisors (3759951).

251912161 is an equidigital number, since it uses as much as digits as its factorization.

251912161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3759950.

The product of its digits is 1080, while the sum is 28.

The square root of 251912161 is about 15871.7409568075. The cubic root of 251912161 is about 631.5625619895.

The spelling of 251912161 in words is "two hundred fifty-one million, nine hundred twelve thousand, one hundred sixty-one".