21443643 has 32 divisors (see below), whose sum is σ = 34496000. Its totient is φ = 13087008.

The previous prime is 21443629. The next prime is 21443657. The reversal of 21443643 is 34634412.

21443643 is a `hidden beast` number, since 2 + 14 + 4 + 3 + 643 = 666.

It is an interprime number because it is at equal distance from previous prime (21443629) and next prime (21443657).

It is not a de Polignac number, because 21443643 - 2⁹ = 21443131 is a prime.

It is a super-2 number, since 2×21443643² = 919659650222898, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (21443623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 69696 + ... + 70002.

It is an arithmetic number, because the mean of its divisors is an integer number (1078000).

Almost surely, 2^21443643 is an apocalyptic number.

21443643 is a deficient number, since it is larger than the sum of its proper divisors (13052357).

21443643 is a wasteful number, since it uses less digits than its factorization.

21443643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 528 (or 522 counting only the distinct ones).

The product of its digits is 6912, while the sum is 27.

The square root of 21443643 is about 4630.7281284912. The cubic root of 21443643 is about 277.8217159948.

The spelling of 21443643 in words is "twenty-one million, four hundred forty-three thousand, six hundred forty-three".