21725543 has 4 divisors (see below), whose sum is σ = 24829200. Its totient is φ = 18621888.

The previous prime is 21725537. The next prime is 21725551. The reversal of 21725543 is 34552712.

It is a happy number.

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 21725543 - 2⁶ = 21725479 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21725533) 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, 1551818 + ... + 1551831.

It is an arithmetic number, because the mean of its divisors is an integer number (6207300).

Almost surely, 2^21725543 is an apocalyptic number.

21725543 is a deficient number, since it is larger than the sum of its proper divisors (3103657).

21725543 is an equidigital number, since it uses as much as digits as its factorization.

21725543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3103656.

The product of its digits is 8400, while the sum is 29.

The square root of 21725543 is about 4661.0667234014. The cubic root of 21725543 is about 279.0338426678.

The spelling of 21725543 in words is "twenty-one million, seven hundred twenty-five thousand, five hundred forty-three".