21700543 has 4 divisors (see below), whose sum is σ = 21866328. Its totient is φ = 21534760.

The previous prime is 21700531. The next prime is 21700559. The reversal of 21700543 is 34500712.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21700543 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 (21700513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 82696 + ... + 82957.

It is an arithmetic number, because the mean of its divisors is an integer number (5466582).

Almost surely, 2^21700543 is an apocalyptic number.

21700543 is a deficient number, since it is larger than the sum of its proper divisors (165785).

21700543 is a wasteful number, since it uses less digits than its factorization.

21700543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165784.

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 21700543 is about 4658.3841619171. The cubic root of 21700543 is about 278.9267717188.

The spelling of 21700543 in words is "twenty-one million, seven hundred thousand, five hundred forty-three".