21724432220 has 24 divisors (see below), whose sum is σ = 45624361104. Its totient is φ = 8689191296.

The previous prime is 21724432217. The next prime is 21724432271. The reversal of 21724432220 is 2223442712.

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, 394499 + ... + 446181.

It is an arithmetic number, because the mean of its divisors is an integer number (1901015046).

Almost surely, 2^21724432220 is an apocalyptic number.

21724432220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21724432220 is an abundant number, since it is smaller than the sum of its proper divisors (23899928884).

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

21724432220 is a wasteful number, since it uses less digits than its factorization.

21724432220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72709 (or 72707 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 29.

Adding to 21724432220 its reverse (2223442712), we get a palindrome (23947874932).

The spelling of 21724432220 in words is "twenty-one billion, seven hundred twenty-four million, four hundred thirty-two thousand, two hundred twenty".