21535043 has 4 divisors (see below), whose sum is σ = 21546888. Its totient is φ = 21523200.

The previous prime is 21535027. The next prime is 21535091. The reversal of 21535043 is 34053512.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21535043 - 2⁴ = 21535027 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21535093) 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, 2558 + ... + 7043.

It is an arithmetic number, because the mean of its divisors is an integer number (5386722).

Almost surely, 2^21535043 is an apocalyptic number.

21535043 is a deficient number, since it is larger than the sum of its proper divisors (11845).

21535043 is an equidigital number, since it uses as much as digits as its factorization.

21535043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11844.

The product of its (nonzero) digits is 1800, while the sum is 23.

The square root of 21535043 is about 4640.5864931062. The cubic root of 21535043 is about 278.2158796223.

Adding to 21535043 its reverse (34053512), we get a palindrome (55588555).

The spelling of 21535043 in words is "twenty-one million, five hundred thirty-five thousand, forty-three".