21116517504 has 128 divisors (see below), whose sum is σ = 59897664000. Its totient is φ = 6576783360.

The previous prime is 21116517503. The next prime is 21116517551. The reversal of 21116517504 is 40571561112.

It is a tau number, because it is divible by the number of its divisors (128).

It is a super-2 number, since 2×21116517504² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21116517503) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 314632 + ... + 375800.

It is an arithmetic number, because the mean of its divisors is an integer number (467950500).

Almost surely, 2^21116517504 is an apocalyptic number.

21116517504 is a gapful number since it is divisible by the number (24) 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 21116517504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29948832000).

21116517504 is an abundant number, since it is smaller than the sum of its proper divisors (38781146496).

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

21116517504 is a wasteful number, since it uses less digits than its factorization.

21116517504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61246 (or 61234 counting only the distinct ones).

The product of its (nonzero) digits is 8400, while the sum is 33.

The spelling of 21116517504 in words is "twenty-one billion, one hundred sixteen million, five hundred seventeen thousand, five hundred four".