15661439 has 2 divisors, whose sum is σ = 15661440. Its totient is φ = 15661438.

The previous prime is 15661423. The next prime is 15661441. The reversal of 15661439 is 93416651.

It is a strong prime.

It is an emirp because it is prime and its reverse (93416651) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 15661439 - 2⁴ = 15661423 is a prime.

Together with 15661441, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 15661399 and 15661408.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15661469) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7830719 + 7830720.

It is an arithmetic number, because the mean of its divisors is an integer number (7830720).

Almost surely, 2^15661439 is an apocalyptic number.

15661439 is a deficient number, since it is larger than the sum of its proper divisors (1).

15661439 is an equidigital number, since it uses as much as digits as its factorization.

15661439 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 19440, while the sum is 35.

The square root of 15661439 is about 3957.4536004860. The cubic root of 15661439 is about 250.1941904545.

The spelling of 15661439 in words is "fifteen million, six hundred sixty-one thousand, four hundred thirty-nine".