251690401 has 4 divisors (see below), whose sum is σ = 255956400. Its totient is φ = 247424404.

The previous prime is 251690399. The next prime is 251690407. The reversal of 251690401 is 104096152.

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 251690401 - 2¹ = 251690399 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 251690401.

It is not an unprimeable number, because it can be changed into a prime (251690407) 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 in 3 ways as a sum of consecutive naturals, for example, 2132911 + ... + 2133028.

It is an arithmetic number, because the mean of its divisors is an integer number (63989100).

Almost surely, 2^251690401 is an apocalyptic number.

It is an amenable number.

251690401 is a deficient number, since it is larger than the sum of its proper divisors (4265999).

251690401 is an equidigital number, since it uses as much as digits as its factorization.

251690401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4265998.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 251690401 is about 15864.7534175606. The cubic root of 251690401 is about 631.3771846335.

The spelling of 251690401 in words is "two hundred fifty-one million, six hundred ninety thousand, four hundred one".