21217110540 has 96 divisors (see below), whose sum is σ = 61459763904. Its totient is φ = 5464719360.

The previous prime is 21217110539. The next prime is 21217110569. The reversal of 21217110540 is 4501171212.

It is a self number, because there is not a number n which added to its sum of digits gives 21217110540.

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, 269260 + ... + 339020.

It is an arithmetic number, because the mean of its divisors is an integer number (640205874).

Almost surely, 2^21217110540 is an apocalyptic number.

21217110540 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 21217110540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30729881952).

21217110540 is an abundant number, since it is smaller than the sum of its proper divisors (40242653364).

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

21217110540 is a wasteful number, since it uses less digits than its factorization.

21217110540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69947 (or 69945 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 24.

Adding to 21217110540 its reverse (4501171212), we get a palindrome (25718281752).

The spelling of 21217110540 in words is "twenty-one billion, two hundred seventeen million, one hundred ten thousand, five hundred forty".