21720333204 has 72 divisors (see below), whose sum is σ = 56737672992. Its totient is φ = 7001668800.

The previous prime is 21720333137. The next prime is 21720333209. The reversal of 21720333204 is 40233302712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21720333209) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 86887 + ... + 225809.

It is an arithmetic number, because the mean of its divisors is an integer number (788023236).

Almost surely, 2^21720333204 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21720333204, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28368836496).

21720333204 is an abundant number, since it is smaller than the sum of its proper divisors (35017339788).

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

21720333204 is a wasteful number, since it uses less digits than its factorization.

21720333204 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 139077 (or 139072 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 27.

Adding to 21720333204 its reverse (40233302712), we get a palindrome (61953635916).

The spelling of 21720333204 in words is "twenty-one billion, seven hundred twenty million, three hundred thirty-three thousand, two hundred four".