21545841312 has 144 divisors (see below), whose sum is σ = 64804914720. Its totient is φ = 6771340800.

The previous prime is 21545841299. The next prime is 21545841319. The reversal of 21545841312 is 21314854512.

21545841312 is a `hidden beast` number, since 2 + 1 + 54 + 584 + 13 + 12 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21545841319) 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, 1145262 + ... + 1163922.

It is an arithmetic number, because the mean of its divisors is an integer number (450034130).

Almost surely, 2^21545841312 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21545841312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32402457360).

21545841312 is an abundant number, since it is smaller than the sum of its proper divisors (43259073408).

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

21545841312 is a wasteful number, since it uses less digits than its factorization.

21545841312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18907 (or 18896 counting only the distinct ones).

The product of its digits is 38400, while the sum is 36.

The spelling of 21545841312 in words is "twenty-one billion, five hundred forty-five million, eight hundred forty-one thousand, three hundred twelve".