21209898 has 16 divisors (see below), whose sum is σ = 42584256. Its totient is φ = 7042560.

The previous prime is 21209873. The next prime is 21209927. The reversal of 21209898 is 89890212.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5143 + ... + 8298.

It is an arithmetic number, because the mean of its divisors is an integer number (2661516).

Almost surely, 2^21209898 is an apocalyptic number.

21209898 is an abundant number, since it is smaller than the sum of its proper divisors (21374358).

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

21209898 is a wasteful number, since it uses less digits than its factorization.

21209898 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13709.

The product of its (nonzero) digits is 20736, while the sum is 39.

The square root of 21209898 is about 4605.4205019737. The cubic root of 21209898 is about 276.8085667462.

The spelling of 21209898 in words is "twenty-one million, two hundred nine thousand, eight hundred ninety-eight".