3661561901 has 2 divisors, whose sum is σ = 3661561902. Its totient is φ = 3661561900.

The previous prime is 3661561853. The next prime is 3661561919. The reversal of 3661561901 is 1091651663.

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., 2347499401 + 1314062500 = 48451^2 + 36250^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3661561901 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3661561301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1830780950 + 1830780951.

It is an arithmetic number, because the mean of its divisors is an integer number (1830780951).

Almost surely, 2^3661561901 is an apocalyptic number.

It is an amenable number.

3661561901 is a deficient number, since it is larger than the sum of its proper divisors (1).

3661561901 is an equidigital number, since it uses as much as digits as its factorization.

3661561901 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 29160, while the sum is 38.

The square root of 3661561901 is about 60510.8411856917. The cubic root of 3661561901 is about 1541.3057319910.

The spelling of 3661561901 in words is "three billion, six hundred sixty-one million, five hundred sixty-one thousand, nine hundred one".