21500007220 has 96 divisors (see below), whose sum is σ = 47934738432. Its totient is φ = 8087040000.

The previous prime is 21500007203. The next prime is 21500007241. The reversal of 21500007220 is 2270000512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6887260 + ... + 6890380.

It is an arithmetic number, because the mean of its divisors is an integer number (499320192).

Almost surely, 2^21500007220 is an apocalyptic number.

21500007220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21500007220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23967369216).

21500007220 is an abundant number, since it is smaller than the sum of its proper divisors (26434731212).

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

21500007220 is a wasteful number, since it uses less digits than its factorization.

21500007220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3473 (or 3471 counting only the distinct ones).

The product of its (nonzero) digits is 280, while the sum is 19.

Adding to 21500007220 its reverse (2270000512), we get a palindrome (23770007732).

The spelling of 21500007220 in words is "twenty-one billion, five hundred million, seven thousand, two hundred twenty".