3961635661 has 2 divisors, whose sum is σ = 3961635662. Its totient is φ = 3961635660.

The previous prime is 3961635533. The next prime is 3961635703. The reversal of 3961635661 is 1665361693.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3502390761 + 459244900 = 59181^2 + 21430^2 .

It is a cyclic number.

It is not a de Polignac number, because 3961635661 - 2⁷ = 3961635533 is a prime.

It is a super-2 number, since 2×3961635661² = 31389114221013813842, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3961635761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1980817830 + 1980817831.

It is an arithmetic number, because the mean of its divisors is an integer number (1980817831).

Almost surely, 2^3961635661 is an apocalyptic number.

It is an amenable number.

3961635661 is a deficient number, since it is larger than the sum of its proper divisors (1).

3961635661 is an equidigital number, since it uses as much as digits as its factorization.

3961635661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 524880, while the sum is 46.

The square root of 3961635661 is about 62941.5257282503. The cubic root of 3961635661 is about 1582.3097741426.

The spelling of 3961635661 in words is "three billion, nine hundred sixty-one million, six hundred thirty-five thousand, six hundred sixty-one".