21672199 has 4 divisors (see below), whose sum is σ = 21817800. Its totient is φ = 21526600.

The previous prime is 21672191. The next prime is 21672221. The reversal of 21672199 is 99127612.

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

It is a cyclic number.

It is not a de Polignac number, because 21672199 - 2³ = 21672191 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21672191) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 72577 + ... + 72874.

It is an arithmetic number, because the mean of its divisors is an integer number (5454450).

Almost surely, 2^21672199 is an apocalyptic number.

21672199 is a deficient number, since it is larger than the sum of its proper divisors (145601).

21672199 is a wasteful number, since it uses less digits than its factorization.

21672199 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145600.

The product of its digits is 13608, while the sum is 37.

The square root of 21672199 is about 4655.3409112545. The cubic root of 21672199 is about 278.8052794440.

It can be divided in two parts, 21 and 672199, that added together give a triangular number (672220 = T₁₁₅₉).

The spelling of 21672199 in words is "twenty-one million, six hundred seventy-two thousand, one hundred ninety-nine".