15663661 has 8 divisors (see below), whose sum is σ = 16901024. Its totient is φ = 14430960.

The previous prime is 15663629. The next prime is 15663671. The reversal of 15663661 is 16636651.

15663661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 15663661 - 2⁵ = 15663629 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 (15663611) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9466 + ... + 10996.

It is an arithmetic number, because the mean of its divisors is an integer number (2112628).

Almost surely, 2^15663661 is an apocalyptic number.

It is an amenable number.

15663661 is a deficient number, since it is larger than the sum of its proper divisors (1237363).

15663661 is a wasteful number, since it uses less digits than its factorization.

15663661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2331.

The product of its digits is 19440, while the sum is 34.

The square root of 15663661 is about 3957.7343266066. The cubic root of 15663661 is about 250.2060221728.

The spelling of 15663661 in words is "fifteen million, six hundred sixty-three thousand, six hundred sixty-one".