997859581 has 2 divisors, whose sum is σ = 997859582. Its totient is φ = 997859580.

The previous prime is 997859573. The next prime is 997859587. The reversal of 997859581 is 185958799.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 981819556 + 16040025 = 31334^2 + 4005^2 .

It is a cyclic number.

It is not a de Polignac number, because 997859581 - 2³ = 997859573 is a prime.

It is a super-2 number, since 2×997859581² = 1991447486786991122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (997859587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 498929790 + 498929791.

It is an arithmetic number, because the mean of its divisors is an integer number (498929791).

Almost surely, 2^997859581 is an apocalyptic number.

It is an amenable number.

997859581 is a deficient number, since it is larger than the sum of its proper divisors (1).

997859581 is an equidigital number, since it uses as much as digits as its factorization.

997859581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8164800, while the sum is 61.

The square root of 997859581 is about 31588.9154767934. The cubic root of 997859581 is about 999.2860173501.

The spelling of 997859581 in words is "nine hundred ninety-seven million, eight hundred fifty-nine thousand, five hundred eighty-one".