15964561 has 4 divisors (see below), whose sum is σ = 16005172. Its totient is φ = 15923952.

The previous prime is 15964549. The next prime is 15964609. The reversal of 15964561 is 16546951.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8910225 + 7054336 = 2985^2 + 2656^2 .

It is a cyclic number.

It is not a de Polignac number, because 15964561 - 2²¹ = 13867409 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 15964561.

It is not an unprimeable number, because it can be changed into a prime (15964061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19710 + ... + 20503.

It is an arithmetic number, because the mean of its divisors is an integer number (4001293).

Almost surely, 2^15964561 is an apocalyptic number.

It is an amenable number.

15964561 is a deficient number, since it is larger than the sum of its proper divisors (40611).

15964561 is an equidigital number, since it uses as much as digits as its factorization.

15964561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40610.

The product of its digits is 32400, while the sum is 37.

The square root of 15964561 is about 3995.5676693056. The cubic root of 15964561 is about 251.7980293597.

The spelling of 15964561 in words is "fifteen million, nine hundred sixty-four thousand, five hundred sixty-one".