21220121999 has 8 divisors (see below), whose sum is σ = 21296910720. Its totient is φ = 21143469600.

The previous prime is 21220121971. The next prime is 21220122029. The reversal of 21220121999 is 99912102212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21220121999 - 2³² = 16925154703 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 (21220121969) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 283109 + ... + 350129.

It is an arithmetic number, because the mean of its divisors is an integer number (2662113840).

Almost surely, 2^21220121999 is an apocalyptic number.

21220121999 is a deficient number, since it is larger than the sum of its proper divisors (76788721).

21220121999 is an equidigital number, since it uses as much as digits as its factorization.

21220121999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68161.

The product of its (nonzero) digits is 11664, while the sum is 38.

The spelling of 21220121999 in words is "twenty-one billion, two hundred twenty million, one hundred twenty-one thousand, nine hundred ninety-nine".