21865540384512 has 144 divisors (see below), whose sum is σ = 70538454389760. Its totient is φ = 6625921305600.

The previous prime is 21865540384507. The next prime is 21865540384543. The reversal of 21865540384512 is 21548304556812.

21865540384512 is a `hidden beast` number, since 2 + 1 + 8 + 6 + 5 + 5 + 40 + 3 + 84 + 512 = 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 (54).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 143715664 + ... + 143867727.

Almost surely, 2^{21865540384512} is an apocalyptic number.

21865540384512 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21865540384512 is an abundant number, since it is smaller than the sum of its proper divisors (48672914005248).

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

21865540384512 is a wasteful number, since it uses less digits than its factorization.

21865540384512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 287583427 (or 287583407 counting only the distinct ones).

The product of its (nonzero) digits is 9216000, while the sum is 54.

The spelling of 21865540384512 in words is "twenty-one trillion, eight hundred sixty-five billion, five hundred forty million, three hundred eighty-four thousand, five hundred twelve".