251720741 has 2 divisors, whose sum is σ = 251720742. Its totient is φ = 251720740.

The previous prime is 251720701. The next prime is 251720743. The reversal of 251720741 is 147027152.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 136072225 + 115648516 = 11665^2 + 10754^2 .

It is a cyclic number.

It is not a de Polignac number, because 251720741 - 2¹⁰ = 251719717 is a prime.

Together with 251720743, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (251720743) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125860370 + 125860371.

It is an arithmetic number, because the mean of its divisors is an integer number (125860371).

Almost surely, 2^251720741 is an apocalyptic number.

It is an amenable number.

251720741 is a deficient number, since it is larger than the sum of its proper divisors (1).

251720741 is an equidigital number, since it uses as much as digits as its factorization.

251720741 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3920, while the sum is 29.

The square root of 251720741 is about 15865.7095964851. The cubic root of 251720741 is about 631.4025533855.

Adding to 251720741 its reverse (147027152), we get a palindrome (398747893).

The spelling of 251720741 in words is "two hundred fifty-one million, seven hundred twenty thousand, seven hundred forty-one".