251047640 has 64 divisors (see below), whose sum is σ = 577886400. Its totient is φ = 98131968.

The previous prime is 251047639. The next prime is 251047651. The reversal of 251047640 is 46740152.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 344957 + ... + 345683.

It is an arithmetic number, because the mean of its divisors is an integer number (9029475).

Almost surely, 2^251047640 is an apocalyptic number.

251047640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 251047640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (288943200).

251047640 is an abundant number, since it is smaller than the sum of its proper divisors (326838760).

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

251047640 is a wasteful number, since it uses less digits than its factorization.

251047640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 924 (or 920 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 29.

The square root of 251047640 is about 15844.4829514882. The cubic root of 251047640 is about 630.8392610818.

Adding to 251047640 its reverse (46740152), we get a palindrome (297787792).

The spelling of 251047640 in words is "two hundred fifty-one million, forty-seven thousand, six hundred forty".