857221586581 has 2 divisors, whose sum is σ = 857221586582. Its totient is φ = 857221586580.

The previous prime is 857221586509. The next prime is 857221586597. The reversal of 857221586581 is 185685122758.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 655993084356 + 201228502225 = 809934^2 + 448585^2 .

It is a cyclic number.

It is not a de Polignac number, because 857221586581 - 2²⁹ = 856684715669 is a prime.

It is a super-2 number, since 2×857221586581² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (857221586681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428610793290 + 428610793291.

It is an arithmetic number, because the mean of its divisors is an integer number (428610793291).

Almost surely, 2^857221586581 is an apocalyptic number.

It is an amenable number.

857221586581 is a deficient number, since it is larger than the sum of its proper divisors (1).

857221586581 is an equidigital number, since it uses as much as digits as its factorization.

857221586581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10752000, while the sum is 58.

The spelling of 857221586581 in words is "eight hundred fifty-seven billion, two hundred twenty-one million, five hundred eighty-six thousand, five hundred eighty-one".