251640342 has 24 divisors (see below), whose sum is σ = 553361016. Its totient is φ = 82627776.

The previous prime is 251640317. The next prime is 251640349. The reversal of 251640342 is 243046152.

251640342 is a `hidden beast` number, since 251 + 6 + 403 + 4 + 2 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251640349) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 103123 + ... + 105534.

It is an arithmetic number, because the mean of its divisors is an integer number (23056709).

Almost surely, 2^251640342 is an apocalyptic number.

251640342 is an abundant number, since it is smaller than the sum of its proper divisors (301720674).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

251640342 is a wasteful number, since it uses less digits than its factorization.

251640342 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208732 (or 208729 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 27.

The square root of 251640342 is about 15863.1756593691. The cubic root of 251640342 is about 631.3353234077.

Adding to 251640342 its reverse (243046152), we get a palindrome (494686494).

The spelling of 251640342 in words is "two hundred fifty-one million, six hundred forty thousand, three hundred forty-two".