251402639 has 4 divisors (see below), whose sum is σ = 257249256. Its totient is φ = 245556024.

The previous prime is 251402621. The next prime is 251402651. The reversal of 251402639 is 936204152.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 251402639 - 2²⁴ = 234625423 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 (251402659) 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, 2923244 + ... + 2923329.

It is an arithmetic number, because the mean of its divisors is an integer number (64312314).

Almost surely, 2^251402639 is an apocalyptic number.

251402639 is a deficient number, since it is larger than the sum of its proper divisors (5846617).

251402639 is an equidigital number, since it uses as much as digits as its factorization.

251402639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5846616.

The product of its (nonzero) digits is 12960, while the sum is 32.

The square root of 251402639 is about 15855.6815999818. The cubic root of 251402639 is about 631.1364713783.

The spelling of 251402639 in words is "two hundred fifty-one million, four hundred two thousand, six hundred thirty-nine".