3991246661 has 2 divisors, whose sum is σ = 3991246662. Its totient is φ = 3991246660.

The previous prime is 3991246613. The next prime is 3991246687. The reversal of 3991246661 is 1666421993.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2108554561 + 1882692100 = 45919^2 + 43390^2 .

It is a cyclic number.

It is not a de Polignac number, because 3991246661 - 2²⁶ = 3924137797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3991246361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1995623330 + 1995623331.

It is an arithmetic number, because the mean of its divisors is an integer number (1995623331).

Almost surely, 2^3991246661 is an apocalyptic number.

It is an amenable number.

3991246661 is a deficient number, since it is larger than the sum of its proper divisors (1).

3991246661 is an equidigital number, since it uses as much as digits as its factorization.

3991246661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 419904, while the sum is 47.

The square root of 3991246661 is about 63176.3140820988. The cubic root of 3991246661 is about 1586.2422846717.

The spelling of 3991246661 in words is "three billion, nine hundred ninety-one million, two hundred forty-six thousand, six hundred sixty-one".