15940409 has 2 divisors, whose sum is σ = 15940410. Its totient is φ = 15940408.

The previous prime is 15940387. The next prime is 15940429. The reversal of 15940409 is 90404951.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15429184 + 511225 = 3928^2 + 715^2 .

It is a cyclic number.

It is not a de Polignac number, because 15940409 - 2⁸ = 15940153 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (15940429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7970204 + 7970205.

It is an arithmetic number, because the mean of its divisors is an integer number (7970205).

Almost surely, 2^15940409 is an apocalyptic number.

It is an amenable number.

15940409 is a deficient number, since it is larger than the sum of its proper divisors (1).

15940409 is an equidigital number, since it uses as much as digits as its factorization.

15940409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6480, while the sum is 32.

The square root of 15940409 is about 3992.5441763367. The cubic root of 15940409 is about 251.6709876505.

The spelling of 15940409 in words is "fifteen million, nine hundred forty thousand, four hundred nine".