251640469 has 4 divisors (see below), whose sum is σ = 254467980. Its totient is φ = 248812960.

The previous prime is 251640421. The next prime is 251640497. The reversal of 251640469 is 964046152.

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 99241444 + 152399025 = 9962^2 + 12345^2 .

It is a cyclic number.

It is not a de Polignac number, because 251640469 - 2⁹ = 251639957 is a prime.

It is a super-2 number, since 2×251640469² = 126645851277079922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251680469) 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, 1413622 + ... + 1413799.

It is an arithmetic number, because the mean of its divisors is an integer number (63616995).

Almost surely, 2^251640469 is an apocalyptic number.

It is an amenable number.

251640469 is a deficient number, since it is larger than the sum of its proper divisors (2827511).

251640469 is an equidigital number, since it uses as much as digits as its factorization.

251640469 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2827510.

The product of its (nonzero) digits is 51840, while the sum is 37.

The square root of 251640469 is about 15863.1796623502. The cubic root of 251640469 is about 631.3354296169.

The spelling of 251640469 in words is "two hundred fifty-one million, six hundred forty thousand, four hundred sixty-nine".