257720401 has 2 divisors, whose sum is σ = 257720402. Its totient is φ = 257720400.

The previous prime is 257720399. The next prime is 257720417. The reversal of 257720401 is 104027752.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 206669376 + 51051025 = 14376^2 + 7145^2 .

It is a cyclic number.

It is not a de Polignac number, because 257720401 - 2¹ = 257720399 is a prime.

Together with 257720399, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 257720401.

It is not a weakly prime, because it can be changed into another prime (257720461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128860200 + 128860201.

It is an arithmetic number, because the mean of its divisors is an integer number (128860201).

Almost surely, 2^257720401 is an apocalyptic number.

It is an amenable number.

257720401 is a deficient number, since it is larger than the sum of its proper divisors (1).

257720401 is an equidigital number, since it uses as much as digits as its factorization.

257720401 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 28.

The square root of 257720401 is about 16053.6725081833. The cubic root of 257720401 is about 636.3796246639.

It can be divided in two parts, 257720 and 401, that added together give a triangular number (258121 = T₇₁₈).

The spelling of 257720401 in words is "two hundred fifty-seven million, seven hundred twenty thousand, four hundred one".