9939661 has 2 divisors, whose sum is σ = 9939662. Its totient is φ = 9939660.

The previous prime is 9939653. The next prime is 9939667. The reversal of 9939661 is 1669399.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9922500 + 17161 = 3150^2 + 131^2 .

It is an emirp because it is prime and its reverse (1669399) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9939661 - 2³ = 9939653 is a prime.

9939661 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9939667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4969830 + 4969831.

It is an arithmetic number, because the mean of its divisors is an integer number (4969831).

Almost surely, 2^9939661 is an apocalyptic number.

It is an amenable number.

9939661 is a deficient number, since it is larger than the sum of its proper divisors (1).

9939661 is an equidigital number, since it uses as much as digits as its factorization.

9939661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 78732, while the sum is 43.

The square root of 9939661 is about 3152.7227914931. The cubic root of 9939661 is about 215.0092730812.

The spelling of 9939661 in words is "nine million, nine hundred thirty-nine thousand, six hundred sixty-one".