21716543 has 4 divisors (see below), whose sum is σ = 22084680. Its totient is φ = 21348408.

The previous prime is 21716533. The next prime is 21716567. The reversal of 21716543 is 34561712.

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 21716543 - 2⁶ = 21716479 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 (21716503) 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, 183980 + ... + 184097.

It is an arithmetic number, because the mean of its divisors is an integer number (5521170).

Almost surely, 2^21716543 is an apocalyptic number.

21716543 is a deficient number, since it is larger than the sum of its proper divisors (368137).

21716543 is an equidigital number, since it uses as much as digits as its factorization.

21716543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 368136.

The product of its digits is 5040, while the sum is 29.

The square root of 21716543 is about 4660.1011791591. The cubic root of 21716543 is about 278.9953065932.

The spelling of 21716543 in words is "twenty-one million, seven hundred sixteen thousand, five hundred forty-three".