21395543 has 16 divisors (see below), whose sum is σ = 24245760. Its totient is φ = 18732384.

The previous prime is 21395527. The next prime is 21395551. The reversal of 21395543 is 34559312.

It is a cyclic number.

It is not a de Polignac number, because 21395543 - 2⁴ = 21395527 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 (21395513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 48518 + ... + 48956.

It is an arithmetic number, because the mean of its divisors is an integer number (1515360).

Almost surely, 2^21395543 is an apocalyptic number.

21395543 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21395543 is a deficient number, since it is larger than the sum of its proper divisors (2850217).

21395543 is a wasteful number, since it uses less digits than its factorization.

21395543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 638.

The product of its digits is 16200, while the sum is 32.

The square root of 21395543 is about 4625.5316451193. The cubic root of 21395543 is about 277.6138342052.

The spelling of 21395543 in words is "twenty-one million, three hundred ninety-five thousand, five hundred forty-three".