1909959661 has 2 divisors, whose sum is σ = 1909959662. Its totient is φ = 1909959660.

The previous prime is 1909959659. The next prime is 1909959677. The reversal of 1909959661 is 1669599091.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1696945636 + 213014025 = 41194^2 + 14595^2 .

It is an emirp because it is prime and its reverse (1669599091) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1909959661 - 2¹ = 1909959659 is a prime.

Together with 1909959659, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1909159661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 954979830 + 954979831.

It is an arithmetic number, because the mean of its divisors is an integer number (954979831).

Almost surely, 2^1909959661 is an apocalyptic number.

It is an amenable number.

1909959661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1909959661 is an equidigital number, since it uses as much as digits as its factorization.

1909959661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1180980, while the sum is 55.

The square root of 1909959661 is about 43703.0852572218. The cubic root of 1909959661 is about 1240.7227102040.

The spelling of 1909959661 in words is "one billion, nine hundred nine million, nine hundred fifty-nine thousand, six hundred sixty-one".