21820199 has 4 divisors (see below), whose sum is σ = 21847536. Its totient is φ = 21792864.

The previous prime is 21820193. The next prime is 21820207. The reversal of 21820199 is 99102812.

It is a happy number.

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 21820199 - 2⁸ = 21819943 is a prime.

It is a super-2 number, since 2×21820199² = 952242168799202, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21820193) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12434 + ... + 14079.

It is an arithmetic number, because the mean of its divisors is an integer number (5461884).

Almost surely, 2^21820199 is an apocalyptic number.

21820199 is a deficient number, since it is larger than the sum of its proper divisors (27337).

21820199 is an equidigital number, since it uses as much as digits as its factorization.

21820199 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27336.

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 21820199 is about 4671.2095863919. The cubic root of 21820199 is about 279.4384963286.

The spelling of 21820199 in words is "twenty-one million, eight hundred twenty thousand, one hundred ninety-nine".