999111661 has 2 divisors, whose sum is σ = 999111662. Its totient is φ = 999111660.

The previous prime is 999111647. The next prime is 999111677. The reversal of 999111661 is 166111999.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 991305225 + 7806436 = 31485^2 + 2794^2 .

It is a cyclic number.

It is not a de Polignac number, because 999111661 - 2¹¹ = 999109613 is a prime.

It is a super-2 number, since 2×999111661² = 1996448222292357842, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999111601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499555830 + 499555831.

It is an arithmetic number, because the mean of its divisors is an integer number (499555831).

Almost surely, 2^999111661 is an apocalyptic number.

It is an amenable number.

999111661 is a deficient number, since it is larger than the sum of its proper divisors (1).

999111661 is an equidigital number, since it uses as much as digits as its factorization.

999111661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 26244, while the sum is 43.

The square root of 999111661 is about 31608.7276080515. The cubic root of 999111661 is about 999.7037992738.

The spelling of 999111661 in words is "nine hundred ninety-nine million, one hundred eleven thousand, six hundred sixty-one".