999170981 has 2 divisors, whose sum is σ = 999170982. Its totient is φ = 999170980.

The previous prime is 999170969. The next prime is 999170987. The reversal of 999170981 is 189071999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 721781956 + 277389025 = 26866^2 + 16655^2 .

It is an emirp because it is prime and its reverse (189071999) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 999170981 - 2¹⁰ = 999169957 is a prime.

It is a super-2 number, since 2×999170981² = 1996685298545004722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999170987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499585490 + 499585491.

It is an arithmetic number, because the mean of its divisors is an integer number (499585491).

Almost surely, 2^999170981 is an apocalyptic number.

It is an amenable number.

999170981 is a deficient number, since it is larger than the sum of its proper divisors (1).

999170981 is an equidigital number, since it uses as much as digits as its factorization.

999170981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 367416, while the sum is 53.

The square root of 999170981 is about 31609.6659425562. The cubic root of 999170981 is about 999.7235839345.

The spelling of 999170981 in words is "nine hundred ninety-nine million, one hundred seventy thousand, nine hundred eighty-one".