257820421 has 2 divisors, whose sum is σ = 257820422. Its totient is φ = 257820420.

The previous prime is 257820361. The next prime is 257820449. The reversal of 257820421 is 124028752.

It is a happy number.

257820421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 223831521 + 33988900 = 14961^2 + 5830^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-257820421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (257820491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128910210 + 128910211.

It is an arithmetic number, because the mean of its divisors is an integer number (128910211).

Almost surely, 2^257820421 is an apocalyptic number.

It is an amenable number.

257820421 is a deficient number, since it is larger than the sum of its proper divisors (1).

257820421 is an equidigital number, since it uses as much as digits as its factorization.

257820421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8960, while the sum is 31.

The square root of 257820421 is about 16056.7873810423. The cubic root of 257820421 is about 636.4619392671.

The spelling of 257820421 in words is "two hundred fifty-seven million, eight hundred twenty thousand, four hundred twenty-one".