21398166 has 12 divisors (see below), whose sum is σ = 46362732. Its totient is φ = 7132716.

The previous prime is 21398141. The next prime is 21398171. The reversal of 21398166 is 66189312.

It is a self number, because there is not a number n which added to its sum of digits gives 21398166.

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, 594376 + ... + 594411.

It is an arithmetic number, because the mean of its divisors is an integer number (3863561).

Almost surely, 2^21398166 is an apocalyptic number.

21398166 is an abundant number, since it is smaller than the sum of its proper divisors (24964566).

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

21398166 is a wasteful number, since it uses less digits than its factorization.

21398166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1188795 (or 1188792 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 21398166 is about 4625.8151714049. The cubic root of 21398166 is about 277.6251784890.

The spelling of 21398166 in words is "twenty-one million, three hundred ninety-eight thousand, one hundred sixty-six".