9990000661 has 2 divisors, whose sum is σ = 9990000662. Its totient is φ = 9990000660.

The previous prime is 9990000659. The next prime is 9990000667. The reversal of 9990000661 is 1660000999.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6299438161 + 3690562500 = 79369^2 + 60750^2 .

It is a cyclic number.

It is not a de Polignac number, because 9990000661 - 2¹ = 9990000659 is a prime.

It is a super-2 number, since 2×9990000661² (a number of 21 digits) contains 22 as substring.

Together with 9990000659, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9990000667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4995000330 + 4995000331.

It is an arithmetic number, because the mean of its divisors is an integer number (4995000331).

Almost surely, 2^9990000661 is an apocalyptic number.

It is an amenable number.

9990000661 is a deficient number, since it is larger than the sum of its proper divisors (1).

9990000661 is an equidigital number, since it uses as much as digits as its factorization.

9990000661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 26244, while the sum is 40.

The square root of 9990000661 is about 99949.9908003998. The cubic root of 9990000661 is about 2153.7163531215.

The spelling of 9990000661 in words is "nine billion, nine hundred ninety million, six hundred sixty-one", and thus it is an aban number.