21043541215 has 4 divisors (see below), whose sum is σ = 25252249464. Its totient is φ = 16834832968.

The previous prime is 21043541213. The next prime is 21043541231. The reversal of 21043541215 is 51214534012.

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 21043541215 - 2¹ = 21043541213 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 (21043541213) 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, 2104354117 + ... + 2104354126.

It is an arithmetic number, because the mean of its divisors is an integer number (6313062366).

Almost surely, 2^21043541215 is an apocalyptic number.

21043541215 is a deficient number, since it is larger than the sum of its proper divisors (4208708249).

21043541215 is an equidigital number, since it uses as much as digits as its factorization.

21043541215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4208708248.

The product of its (nonzero) digits is 4800, while the sum is 28.

The spelling of 21043541215 in words is "twenty-one billion, forty-three million, five hundred forty-one thousand, two hundred fifteen".