2557166861 has 2 divisors, whose sum is σ = 2557166862. Its totient is φ = 2557166860.

The previous prime is 2557166797. The next prime is 2557166863. The reversal of 2557166861 is 1686617552.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2067429961 + 489736900 = 45469^2 + 22130^2 .

It is a cyclic number.

It is not a de Polignac number, because 2557166861 - 2⁶ = 2557166797 is a prime.

Together with 2557166863, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2557166863) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1278583430 + 1278583431.

It is an arithmetic number, because the mean of its divisors is an integer number (1278583431).

Almost surely, 2^2557166861 is an apocalyptic number.

It is an amenable number.

2557166861 is a deficient number, since it is larger than the sum of its proper divisors (1).

2557166861 is an equidigital number, since it uses as much as digits as its factorization.

2557166861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 604800, while the sum is 47.

The square root of 2557166861 is about 50568.4373992315. The cubic root of 2557166861 is about 1367.4759252780.

The spelling of 2557166861 in words is "two billion, five hundred fifty-seven million, one hundred sixty-six thousand, eight hundred sixty-one".