251255444440 has 512 divisors, whose sum is σ = 816102604800. Its totient is φ = 67017922560.

The previous prime is 251255444437. The next prime is 251255444449. The reversal of 251255444440 is 44444552152.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 251255444393 and 251255444402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251255444449) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 35752207 + ... + 35759233.

It is an arithmetic number, because the mean of its divisors is an integer number (1593950400).

Almost surely, 2^251255444440 is an apocalyptic number.

251255444440 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 251255444440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (408051302400).

251255444440 is an abundant number, since it is smaller than the sum of its proper divisors (564847160360).

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

251255444440 is a wasteful number, since it uses less digits than its factorization.

251255444440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7135 (or 7131 counting only the distinct ones).

The product of its (nonzero) digits is 512000, while the sum is 40.

Adding to 251255444440 its reverse (44444552152), we get a palindrome (295699996592).

The spelling of 251255444440 in words is "two hundred fifty-one billion, two hundred fifty-five million, four hundred forty-four thousand, four hundred forty".