21166686 has 12 divisors (see below), whose sum is σ = 45861192. Its totient is φ = 7055556.

The previous prime is 21166679. The next prime is 21166711. The reversal of 21166686 is 68666112.

It is a self number, because there is not a number n which added to its sum of digits gives 21166686.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 587946 + ... + 587981.

It is an arithmetic number, because the mean of its divisors is an integer number (3821766).

Almost surely, 2^21166686 is an apocalyptic number.

21166686 is an abundant number, since it is smaller than the sum of its proper divisors (24694506).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21166686 is a wasteful number, since it uses less digits than its factorization.

21166686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1175935 (or 1175932 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 21166686 is about 4600.7266817319. The cubic root of 21166686 is about 276.6204535641.

The spelling of 21166686 in words is "twenty-one million, one hundred sixty-six thousand, six hundred eighty-six".