21644229873 has 40 divisors (see below), whose sum is σ = 33714090848. Its totient is φ = 12350765952.

The previous prime is 21644229821. The next prime is 21644229907. The reversal of 21644229873 is 37892244612.

It is not a de Polignac number, because 21644229873 - 2¹⁰ = 21644228849 is a prime.

It is a super-2 number, since 2×21644229873² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21644229073) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 6531465 + ... + 6534777.

Almost surely, 2^21644229873 is an apocalyptic number.

It is an amenable number.

21644229873 is a deficient number, since it is larger than the sum of its proper divisors (12069860975).

21644229873 is an frugal number, since it uses more digits than its factorization.

21644229873 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4251 (or 4230 counting only the distinct ones).

The product of its digits is 1161216, while the sum is 48.

The spelling of 21644229873 in words is "twenty-one billion, six hundred forty-four million, two hundred twenty-nine thousand, eight hundred seventy-three".