21643133544 has 24 divisors (see below), whose sum is σ = 58616820210. Its totient is φ = 7214377824.

The previous prime is 21643133539. The next prime is 21643133581. The reversal of 21643133544 is 44533134612.

21643133544 is a `hidden beast` number, since 2 + 1 + 643 + 1 + 3 + 3 + 5 + 4 + 4 = 666.

It can be written as a sum of positive squares in only one way, i.e., 21130111044 + 513022500 = 145362^2 + 22650^2 .

It is a tau number, because it is divible by the number of its divisors (24).

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

It is a junction number, because it is equal to n+sod(n) for n = 21643133499 and 21643133508.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 150299467 + ... + 150299610.

Almost surely, 2^21643133544 is an apocalyptic number.

21643133544 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21643133544 is an abundant number, since it is smaller than the sum of its proper divisors (36973686666).

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

21643133544 is a wasteful number, since it uses less digits than its factorization.

21643133544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 300599089 (or 300599082 counting only the distinct ones).

The product of its digits is 103680, while the sum is 36.

The spelling of 21643133544 in words is "twenty-one billion, six hundred forty-three million, one hundred thirty-three thousand, five hundred forty-four".