21347843 has 4 divisors (see below), whose sum is σ = 23288568. Its totient is φ = 19407120.

The previous prime is 21347827. The next prime is 21347863. The reversal of 21347843 is 34874312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21347843 - 2⁴ = 21347827 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21347803) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 970346 + ... + 970367.

It is an arithmetic number, because the mean of its divisors is an integer number (5822142).

Almost surely, 2^21347843 is an apocalyptic number.

21347843 is a deficient number, since it is larger than the sum of its proper divisors (1940725).

21347843 is a wasteful number, since it uses less digits than its factorization.

21347843 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1940724.

The product of its digits is 16128, while the sum is 32.

The square root of 21347843 is about 4620.3726040223. The cubic root of 21347843 is about 277.4073732465.

The spelling of 21347843 in words is "twenty-one million, three hundred forty-seven thousand, eight hundred forty-three".