999917661 has 8 divisors (see below), whose sum is σ = 1340204544. Its totient is φ = 663121280.

The previous prime is 999917623. The next prime is 999917669. The reversal of 999917661 is 166719999.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 999917661 - 2¹⁰ = 999916637 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999917669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 871956 + ... + 873101.

It is an arithmetic number, because the mean of its divisors is an integer number (167525568).

Almost surely, 2^999917661 is an apocalyptic number.

It is an amenable number.

999917661 is a deficient number, since it is larger than the sum of its proper divisors (340286883).

999917661 is a wasteful number, since it uses less digits than its factorization.

999917661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1745251.

The product of its digits is 1653372, while the sum is 57.

The square root of 999917661 is about 31621.4746809822. The cubic root of 999917661 is about 999.9725529133.

The spelling of 999917661 in words is "nine hundred ninety-nine million, nine hundred seventeen thousand, six hundred sixty-one".