257728421 has 8 divisors (see below), whose sum is σ = 264944664. Its totient is φ = 250525440.

The previous prime is 257728411. The next prime is 257728433. The reversal of 257728421 is 124827752.

It can be written as a sum of positive squares in 4 ways, for example, as 151019521 + 106708900 = 12289^2 + 10330^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 257728421 - 2⁶ = 257728357 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (257728411) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 46241 + ... + 51513.

It is an arithmetic number, because the mean of its divisors is an integer number (33118083).

Almost surely, 2^257728421 is an apocalyptic number.

It is an amenable number.

257728421 is a deficient number, since it is larger than the sum of its proper divisors (7216243).

257728421 is a wasteful number, since it uses less digits than its factorization.

257728421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6631.

The product of its digits is 62720, while the sum is 38.

The square root of 257728421 is about 16053.9222933213. The cubic root of 257728421 is about 636.3862257603.

The spelling of 257728421 in words is "two hundred fifty-seven million, seven hundred twenty-eight thousand, four hundred twenty-one".