15919661 has 2 divisors, whose sum is σ = 15919662. Its totient is φ = 15919660.

The previous prime is 15919639. The next prime is 15919681. The reversal of 15919661 is 16691951.

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., 14394436 + 1525225 = 3794^2 + 1235^2 .

It is a cyclic number.

It is not a de Polignac number, because 15919661 - 2¹⁸ = 15657517 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 (15919601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7959830 + 7959831.

It is an arithmetic number, because the mean of its divisors is an integer number (7959831).

Almost surely, 2^15919661 is an apocalyptic number.

It is an amenable number.

15919661 is a deficient number, since it is larger than the sum of its proper divisors (1).

15919661 is an equidigital number, since it uses as much as digits as its factorization.

15919661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14580, while the sum is 38.

The square root of 15919661 is about 3989.9449870894. The cubic root of 15919661 is about 251.5617487806.

The spelling of 15919661 in words is "fifteen million, nine hundred nineteen thousand, six hundred sixty-one".