21188998 has 4 divisors (see below), whose sum is σ = 31783500. Its totient is φ = 10594498.

The previous prime is 21188983. The next prime is 21189017. The reversal of 21188998 is 89988112.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5297248 + ... + 5297251.

It is an arithmetic number, because the mean of its divisors is an integer number (7945875).

Almost surely, 2^21188998 is an apocalyptic number.

21188998 is a deficient number, since it is larger than the sum of its proper divisors (10594502).

21188998 is a wasteful number, since it uses less digits than its factorization.

21188998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10594501.

The product of its digits is 82944, while the sum is 46.

The square root of 21188998 is about 4603.1508773882. The cubic root of 21188998 is about 276.7176154941.

The spelling of 21188998 in words is "twenty-one million, one hundred eighty-eight thousand, nine hundred ninety-eight".