251509240 has 16 divisors (see below), whose sum is σ = 565895880. Its totient is φ = 100603680.

The previous prime is 251509229. The next prime is 251509243. The reversal of 251509240 is 42905152.

It is a junction number, because it is equal to n+sod(n) for n = 251509199 and 251509208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251509243) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3143826 + ... + 3143905.

Almost surely, 2^251509240 is an apocalyptic number.

251509240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

251509240 is an abundant number, since it is smaller than the sum of its proper divisors (314386640).

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

251509240 is a wasteful number, since it uses less digits than its factorization.

251509240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6287742 (or 6287738 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 28.

The square root of 251509240 is about 15859.0428462754. The cubic root of 251509240 is about 631.2256646502.

The spelling of 251509240 in words is "two hundred fifty-one million, five hundred nine thousand, two hundred forty".