251240987 has 2 divisors, whose sum is σ = 251240988. Its totient is φ = 251240986.

The previous prime is 251240981. The next prime is 251241013. The reversal of 251240987 is 789042152.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 251240987 - 2¹² = 251236891 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 251240987.

It is not a weakly prime, because it can be changed into another prime (251240981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125620493 + 125620494.

It is an arithmetic number, because the mean of its divisors is an integer number (125620494).

Almost surely, 2^251240987 is an apocalyptic number.

251240987 is a deficient number, since it is larger than the sum of its proper divisors (1).

251240987 is an equidigital number, since it uses as much as digits as its factorization.

251240987 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40320, while the sum is 38.

The square root of 251240987 is about 15850.5831753914. The cubic root of 251240987 is about 631.0011687043.

The spelling of 251240987 in words is "two hundred fifty-one million, two hundred forty thousand, nine hundred eighty-seven".