251321240 has 32 divisors (see below), whose sum is σ = 578627280. Its totient is φ = 98189952.

The previous prime is 251321237. The next prime is 251321243. The reversal of 251321240 is 42123152.

It is an interprime number because it is at equal distance from previous prime (251321237) and next prime (251321243).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251321243) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 71339 + ... + 74778.

Almost surely, 2^251321240 is an apocalyptic number.

251321240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

251321240 is an abundant number, since it is smaller than the sum of its proper divisors (327306040).

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

251321240 is a wasteful number, since it uses less digits than its factorization.

251321240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 146171 (or 146167 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 251321240 is about 15853.1145204972. The cubic root of 251321240 is about 631.0683476924.

Adding to 251321240 its reverse (42123152), we get a palindrome (293444392).

The spelling of 251321240 in words is "two hundred fifty-one million, three hundred twenty-one thousand, two hundred forty".