857981 has 2 divisors, whose sum is σ = 857982. Its totient is φ = 857980.

The previous prime is 857977. The next prime is 858001. The reversal of 857981 is 189758.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 538756 + 319225 = 734^2 + 565^2 .

It is a cyclic number.

It is not a de Polignac number, because 857981 - 2² = 857977 is a prime.

It is a super-2 number, since 2×857981² = 1472262792722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (857951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428990 + 428991.

It is an arithmetic number, because the mean of its divisors is an integer number (428991).

2⁸⁵⁷⁹⁸¹ is an apocalyptic number.

It is an amenable number.

857981 is a deficient number, since it is larger than the sum of its proper divisors (1).

857981 is an equidigital number, since it uses as much as digits as its factorization.

857981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20160, while the sum is 38.

The square root of 857981 is about 926.2726380499. The cubic root of 857981 is about 95.0223770002.

The spelling of 857981 in words is "eight hundred fifty-seven thousand, nine hundred eighty-one".