257720531 has 2 divisors, whose sum is σ = 257720532. Its totient is φ = 257720530.

The previous prime is 257720513. The next prime is 257720539. The reversal of 257720531 is 135027752.

257720531 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

Together with previous prime (257720513) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-257720531 is a prime.

It is a super-2 number, since 2×257720531² = 132839744197843922, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (257720539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128860265 + 128860266.

It is an arithmetic number, because the mean of its divisors is an integer number (128860266).

Almost surely, 2^257720531 is an apocalyptic number.

257720531 is a deficient number, since it is larger than the sum of its proper divisors (1).

257720531 is an equidigital number, since it uses as much as digits as its factorization.

257720531 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 14700, while the sum is 32.

The square root of 257720531 is about 16053.6765571006. The cubic root of 257720531 is about 636.3797316653.

The spelling of 257720531 in words is "two hundred fifty-seven million, seven hundred twenty thousand, five hundred thirty-one".