21021199 has 4 divisors (see below), whose sum is σ = 21099040. Its totient is φ = 20943360.

The previous prime is 21021181. The next prime is 21021229. The reversal of 21021199 is 99112012.

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 21021199 - 2¹¹ = 21019151 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 (21021499) 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, 38514 + ... + 39055.

It is an arithmetic number, because the mean of its divisors is an integer number (5274760).

Almost surely, 2^21021199 is an apocalyptic number.

21021199 is a deficient number, since it is larger than the sum of its proper divisors (77841).

21021199 is an equidigital number, since it uses as much as digits as its factorization.

21021199 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77840.

The product of its (nonzero) digits is 324, while the sum is 25.

The square root of 21021199 is about 4584.8881120481. Note that the first 3 decimals coincide. The cubic root of 21021199 is about 275.9852220261.

It can be divided in two parts, 2 and 1021199, that added together give a palindrome (1021201).

The spelling of 21021199 in words is "twenty-one million, twenty-one thousand, one hundred ninety-nine".