21198618 has 32 divisors (see below), whose sum is σ = 53838720. Its totient is φ = 6056640.

The previous prime is 21198559. The next prime is 21198631. The reversal of 21198618 is 81689112.

21198618 is a `hidden beast` number, since 21 + 19 + 8 + 618 = 666.

It is a Curzon number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 27663 + ... + 28418.

It is an arithmetic number, because the mean of its divisors is an integer number (1682460).

Almost surely, 2^21198618 is an apocalyptic number.

21198618 is an abundant number, since it is smaller than the sum of its proper divisors (32640102).

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

21198618 is a wasteful number, since it uses less digits than its factorization.

21198618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56099 (or 56093 counting only the distinct ones).

The product of its digits is 6912, while the sum is 36.

The square root of 21198618 is about 4604.1956952328. The cubic root of 21198618 is about 276.7594866057.

The spelling of 21198618 in words is "twenty-one million, one hundred ninety-eight thousand, six hundred eighteen".