866219857 has 2 divisors, whose sum is σ = 866219858. Its totient is φ = 866219856.

The previous prime is 866219831. The next prime is 866219867. The reversal of 866219857 is 758912668.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 673454401 + 192765456 = 25951^2 + 13884^2 .

It is a cyclic number.

It is not a de Polignac number, because 866219857 - 2¹⁹ = 865695569 is a prime.

It is a super-2 number, since 2×866219857² = 1500673681322200898, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (866219867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 433109928 + 433109929.

It is an arithmetic number, because the mean of its divisors is an integer number (433109929).

Almost surely, 2^866219857 is an apocalyptic number.

It is an amenable number.

866219857 is a deficient number, since it is larger than the sum of its proper divisors (1).

866219857 is an equidigital number, since it uses as much as digits as its factorization.

866219857 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1451520, while the sum is 52.

The square root of 866219857 is about 29431.6132245584. The cubic root of 866219857 is about 953.2556288104.

The spelling of 866219857 in words is "eight hundred sixty-six million, two hundred nineteen thousand, eight hundred fifty-seven".