15966661 has 4 divisors (see below), whose sum is σ = 15978924. Its totient is φ = 15954400.

The previous prime is 15966659. The next prime is 15966739. The reversal of 15966661 is 16666951.

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 5688225 + 10278436 = 2385^2 + 3206^2 .

It is a cyclic number.

It is not a de Polignac number, because 15966661 - 2¹ = 15966659 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15960661) 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, 3910 + ... + 6871.

It is an arithmetic number, because the mean of its divisors is an integer number (3994731).

Almost surely, 2^15966661 is an apocalyptic number.

It is an amenable number.

15966661 is a deficient number, since it is larger than the sum of its proper divisors (12263).

15966661 is a wasteful number, since it uses less digits than its factorization.

15966661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12262.

The product of its digits is 58320, while the sum is 40.

The square root of 15966661 is about 3995.8304518585. The cubic root of 15966661 is about 251.8090694937.

The spelling of 15966661 in words is "fifteen million, nine hundred sixty-six thousand, six hundred sixty-one".