21265616600 has 96 divisors (see below), whose sum is σ = 50295590400. Its totient is φ = 8360755200.

The previous prime is 21265616551. The next prime is 21265616609. The reversal of 21265616600 is 661656212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21265616609) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2764760 + ... + 2772440.

It is an arithmetic number, because the mean of its divisors is an integer number (523912400).

Almost surely, 2^21265616600 is an apocalyptic number.

21265616600 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 21265616600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25147795200).

21265616600 is an abundant number, since it is smaller than the sum of its proper divisors (29029973800).

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

21265616600 is a wasteful number, since it uses less digits than its factorization.

21265616600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7933 (or 7924 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 35.

The spelling of 21265616600 in words is "twenty-one billion, two hundred sixty-five million, six hundred sixteen thousand, six hundred".