251051640 has 192 divisors, whose sum is σ = 892270080. Its totient is φ = 55353600.

The previous prime is 251051629. The next prime is 251051657. The reversal of 251051640 is 46150152.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 251051640.

It is a congruent number.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 807085 + ... + 807395.

It is an arithmetic number, because the mean of its divisors is an integer number (4647240).

Almost surely, 2^251051640 is an apocalyptic number.

251051640 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 251051640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (446135040).

251051640 is an abundant number, since it is smaller than the sum of its proper divisors (641218440).

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

251051640 is a wasteful number, since it uses less digits than its factorization.

251051640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 394 (or 359 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 251051640 is about 15844.6091778876. The cubic root of 251051640 is about 630.8426114998.

The spelling of 251051640 in words is "two hundred fifty-one million, fifty-one thousand, six hundred forty".