21220099 has 4 divisors (see below), whose sum is σ = 22142736. Its totient is φ = 20297464.

The previous prime is 21220019. The next prime is 21220103. The reversal of 21220099 is 99002212.

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 21220099 - 2²¹ = 19122947 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21220019) 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, 461284 + ... + 461329.

It is an arithmetic number, because the mean of its divisors is an integer number (5535684).

Almost surely, 2^21220099 is an apocalyptic number.

21220099 is a deficient number, since it is larger than the sum of its proper divisors (922637).

21220099 is an equidigital number, since it uses as much as digits as its factorization.

21220099 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 922636.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 21220099 is about 4606.5278681454. The cubic root of 21220099 is about 276.8529370934.

The spelling of 21220099 in words is "twenty-one million, two hundred twenty thousand, ninety-nine".