21738543 has 4 divisors (see below), whose sum is σ = 28984728. Its totient is φ = 14492360.

The previous prime is 21738539. The next prime is 21738547. The reversal of 21738543 is 34583712.

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

It is an interprime number because it is at equal distance from previous prime (21738539) and next prime (21738547).

It is a cyclic number.

It is not a de Polignac number, because 21738543 - 2² = 21738539 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21738547) 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, 3623088 + ... + 3623093.

It is an arithmetic number, because the mean of its divisors is an integer number (7246182).

Almost surely, 2^21738543 is an apocalyptic number.

21738543 is a deficient number, since it is larger than the sum of its proper divisors (7246185).

21738543 is an equidigital number, since it uses as much as digits as its factorization.

21738543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7246184.

The product of its digits is 20160, while the sum is 33.

The square root of 21738543 is about 4662.4610454137. The cubic root of 21738543 is about 279.0894871025.

The spelling of 21738543 in words is "twenty-one million, seven hundred thirty-eight thousand, five hundred forty-three".