15909961 has 2 divisors, whose sum is σ = 15909962. Its totient is φ = 15909960.

The previous prime is 15909919. The next prime is 15909989. The reversal of 15909961 is 16990951.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11833600 + 4076361 = 3440^2 + 2019^2 .

It is a cyclic number.

It is not a de Polignac number, because 15909961 - 2⁷ = 15909833 is a prime.

It is not a weakly prime, because it can be changed into another prime (15919961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7954980 + 7954981.

It is an arithmetic number, because the mean of its divisors is an integer number (7954981).

Almost surely, 2^15909961 is an apocalyptic number.

It is an amenable number.

15909961 is a deficient number, since it is larger than the sum of its proper divisors (1).

15909961 is an equidigital number, since it uses as much as digits as its factorization.

15909961 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 21870, while the sum is 40.

The square root of 15909961 is about 3988.7292462638. The cubic root of 15909961 is about 251.5106454158.

The spelling of 15909961 in words is "fifteen million, nine hundred nine thousand, nine hundred sixty-one".