21985365600 has 576 divisors, whose sum is σ = 91861620480. Its totient is φ = 5015347200.

The previous prime is 21985365559. The next prime is 21985365601. The reversal of 21985365600 is 656358912.

21985365600 is a `hidden beast` number, since 2 + 1 + 9 + 8 + 5 + 36 + 5 + 600 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21985365601) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 4036479 + ... + 4041921.

It is an arithmetic number, because the mean of its divisors is an integer number (159481980).

Almost surely, 2^21985365600 is an apocalyptic number.

21985365600 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 21985365600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45930810240).

21985365600 is an abundant number, since it is smaller than the sum of its proper divisors (69876254880).

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

21985365600 is a wasteful number, since it uses less digits than its factorization.

21985365600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5500 (or 5481 counting only the distinct ones).

The product of its (nonzero) digits is 388800, while the sum is 45.

The spelling of 21985365600 in words is "twenty-one billion, nine hundred eighty-five million, three hundred sixty-five thousand, six hundred".