9994999661 has 2 divisors, whose sum is σ = 9994999662. Its totient is φ = 9994999660.

The previous prime is 9994999643. The next prime is 9994999681. The reversal of 9994999661 is 1669994999.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9394455625 + 600544036 = 96925^2 + 24506^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9994999661 is a prime.

It is a super-2 number, since 2×9994999661² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9994999681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4997499830 + 4997499831.

It is an arithmetic number, because the mean of its divisors is an integer number (4997499831).

Almost surely, 2^9994999661 is an apocalyptic number.

It is an amenable number.

9994999661 is a deficient number, since it is larger than the sum of its proper divisors (1).

9994999661 is an equidigital number, since it uses as much as digits as its factorization.

9994999661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 76527504, while the sum is 71.

The square root of 9994999661 is about 99974.9951787946. The cubic root of 9994999661 is about 2154.0755333683.

The spelling of 9994999661 in words is "nine billion, nine hundred ninety-four million, nine hundred ninety-nine thousand, six hundred sixty-one".