251311440040 has 64 divisors (see below), whose sum is σ = 569924586000. Its totient is φ = 99730839552.

The previous prime is 251311440019. The next prime is 251311440049. The reversal of 251311440040 is 40044113152.

It can be written as a sum of positive squares in 8 ways, for example, as 23631683076 + 227679756964 = 153726^2 + 477158^2 .

It is a junction number, because it is equal to n+sod(n) for n = 251311439987 and 251311440014.

It is not an unprimeable number, because it can be changed into a prime (251311440049) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5059164 + ... + 5108596.

Almost surely, 2^251311440040 is an apocalyptic number.

251311440040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

251311440040 is an abundant number, since it is smaller than the sum of its proper divisors (318613145960).

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

251311440040 is a wasteful number, since it uses less digits than its factorization.

251311440040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50446 (or 50442 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 25.

Adding to 251311440040 its reverse (40044113152), we get a palindrome (291355553192).

The spelling of 251311440040 in words is "two hundred fifty-one billion, three hundred eleven million, four hundred forty thousand, forty".