21655642200 has 96 divisors (see below), whose sum is σ = 67480688400. Its totient is φ = 5744885760.

The previous prime is 21655642189. The next prime is 21655642201. The reversal of 21655642200 is 224655612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21655642201) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 22296 + ... + 209304.

Almost surely, 2^21655642200 is an apocalyptic number.

21655642200 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 21655642200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33740344200).

21655642200 is an abundant number, since it is smaller than the sum of its proper divisors (45825046200).

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

21655642200 is a wasteful number, since it uses less digits than its factorization.

21655642200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 187221 (or 187212 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 33.

The spelling of 21655642200 in words is "twenty-one billion, six hundred fifty-five million, six hundred forty-two thousand, two hundred".