251249021 has 2 divisors, whose sum is σ = 251249022. Its totient is φ = 251249020.

The previous prime is 251248997. The next prime is 251249029. The reversal of 251249021 is 120942152.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 207504025 + 43744996 = 14405^2 + 6614^2 .

It is a cyclic number.

It is not a de Polignac number, because 251249021 - 2¹⁴ = 251232637 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (251249029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125624510 + 125624511.

It is an arithmetic number, because the mean of its divisors is an integer number (125624511).

Almost surely, 2^251249021 is an apocalyptic number.

It is an amenable number.

251249021 is a deficient number, since it is larger than the sum of its proper divisors (1).

251249021 is an equidigital number, since it uses as much as digits as its factorization.

251249021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 251249021 is about 15850.8366025267. The cubic root of 251249021 is about 631.0078945301.

The spelling of 251249021 in words is "two hundred fifty-one million, two hundred forty-nine thousand, twenty-one".