21222156621 has 8 divisors (see below), whose sum is σ = 28333591264. Its totient is φ = 14129413200.

The previous prime is 21222156619. The next prime is 21222156623. The reversal of 21222156621 is 12665122212.

It is an interprime number because it is at equal distance from previous prime (21222156619) and next prime (21222156623).

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

It is not a de Polignac number, because 21222156621 - 2¹ = 21222156619 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 (21222156623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4670155 + ... + 4674696.

It is an arithmetic number, because the mean of its divisors is an integer number (3541698908).

Almost surely, 2^21222156621 is an apocalyptic number.

It is an amenable number.

21222156621 is a deficient number, since it is larger than the sum of its proper divisors (7111434643).

21222156621 is an equidigital number, since it uses as much as digits as its factorization.

21222156621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9345611.

The product of its digits is 5760, while the sum is 30.

Adding to 21222156621 its reverse (12665122212), we get a palindrome (33887278833).

The spelling of 21222156621 in words is "twenty-one billion, two hundred twenty-two million, one hundred fifty-six thousand, six hundred twenty-one".