21049543 has 2 divisors, whose sum is σ = 21049544. Its totient is φ = 21049542.

The previous prime is 21049541. The next prime is 21049573. The reversal of 21049543 is 34594012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21049543 - 2¹ = 21049541 is a prime.

Together with 21049541, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21049541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10524771 + 10524772.

It is an arithmetic number, because the mean of its divisors is an integer number (10524772).

Almost surely, 2^21049543 is an apocalyptic number.

21049543 is a deficient number, since it is larger than the sum of its proper divisors (1).

21049543 is an equidigital number, since it uses as much as digits as its factorization.

21049543 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 21049543 is about 4587.9780949782. The cubic root of 21049543 is about 276.1092081654.

The spelling of 21049543 in words is "twenty-one million, forty-nine thousand, five hundred forty-three".