21493843 has 16 divisors (see below), whose sum is σ = 25663680. Its totient is φ = 17611776.

The previous prime is 21493841. The next prime is 21493847. The reversal of 21493843 is 34839412.

It is not a de Polignac number, because 21493843 - 2¹ = 21493841 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21493799 and 21493808.

It is not an unprimeable number, because it can be changed into a prime (21493841) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22471 + ... + 23407.

It is an arithmetic number, because the mean of its divisors is an integer number (1603980).

Almost surely, 2^21493843 is an apocalyptic number.

21493843 is a deficient number, since it is larger than the sum of its proper divisors (4169837).

21493843 is a wasteful number, since it uses less digits than its factorization.

21493843 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1086.

The product of its digits is 20736, while the sum is 34.

The square root of 21493843 is about 4636.1452738239. The cubic root of 21493843 is about 278.0383424505.

The spelling of 21493843 in words is "twenty-one million, four hundred ninety-three thousand, eight hundred forty-three".