257643454861 has 4 divisors (see below), whose sum is σ = 277462182172. Its totient is φ = 237824727552.

The previous prime is 257643454853. The next prime is 257643454877. The reversal of 257643454861 is 168454346752.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 29264602761 + 228378852100 = 171069^2 + 477890^2 .

It is a cyclic number.

It is not a de Polignac number, because 257643454861 - 2³ = 257643454853 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 (257643454361) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9909363636 + ... + 9909363661.

It is an arithmetic number, because the mean of its divisors is an integer number (69365545543).

Almost surely, 2^257643454861 is an apocalyptic number.

It is an amenable number.

257643454861 is a deficient number, since it is larger than the sum of its proper divisors (19818727311).

257643454861 is a wasteful number, since it uses less digits than its factorization.

257643454861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19818727310.

The product of its digits is 19353600, while the sum is 55.

The spelling of 257643454861 in words is "two hundred fifty-seven billion, six hundred forty-three million, four hundred fifty-four thousand, eight hundred sixty-one".