21511323320 has 64 divisors (see below), whose sum is σ = 51387799680. Its totient is φ = 8076220416.

The previous prime is 21511323313. The next prime is 21511323331. The reversal of 21511323320 is 2332311512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 206462 + ... + 292658.

It is an arithmetic number, because the mean of its divisors is an integer number (802934370).

Almost surely, 2^21511323320 is an apocalyptic number.

21511323320 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 21511323320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25693899840).

21511323320 is an abundant number, since it is smaller than the sum of its proper divisors (29876476360).

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

21511323320 is a wasteful number, since it uses less digits than its factorization.

21511323320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86592 (or 86588 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 23.

Adding to 21511323320 its reverse (2332311512), we get a palindrome (23843634832).

The spelling of 21511323320 in words is "twenty-one billion, five hundred eleven million, three hundred twenty-three thousand, three hundred twenty".