21721443324 has 24 divisors (see below), whose sum is σ = 57923849088. Its totient is φ = 6206126640.

The previous prime is 21721443313. The next prime is 21721443353. The reversal of 21721443324 is 42334412712.

It is a happy number.

It is a super-2 number, since 2×21721443324² (a number of 21 digits) contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 129294222 + ... + 129294389.

It is an arithmetic number, because the mean of its divisors is an integer number (2413493712).

Almost surely, 2^21721443324 is an apocalyptic number.

It is an amenable number.

21721443324 is an abundant number, since it is smaller than the sum of its proper divisors (36202405764).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21721443324 is a wasteful number, since it uses less digits than its factorization.

21721443324 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 258588625 (or 258588623 counting only the distinct ones).

The product of its digits is 32256, while the sum is 33.

The spelling of 21721443324 in words is "twenty-one billion, seven hundred twenty-one million, four hundred forty-three thousand, three hundred twenty-four".