21423843 has 12 divisors (see below), whose sum is σ = 35366448. Its totient is φ = 12242160.

The previous prime is 21423827. The next prime is 21423863. The reversal of 21423843 is 34832412.

It is not a de Polignac number, because 21423843 - 2⁴ = 21423827 is a prime.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21423823) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 169968 + ... + 170093.

It is an arithmetic number, because the mean of its divisors is an integer number (2947204).

Almost surely, 2^21423843 is an apocalyptic number.

21423843 is a deficient number, since it is larger than the sum of its proper divisors (13942605).

21423843 is a wasteful number, since it uses less digits than its factorization.

21423843 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340074 (or 340071 counting only the distinct ones).

The product of its digits is 4608, while the sum is 27.

The square root of 21423843 is about 4628.5897420273. The cubic root of 21423843 is about 277.7361807164.

The spelling of 21423843 in words is "twenty-one million, four hundred twenty-three thousand, eight hundred forty-three".