21543515205 has 8 divisors (see below), whose sum is σ = 34469624352. Its totient is φ = 11489874768.

The previous prime is 21543515197. The next prime is 21543515219. The reversal of 21543515205 is 50251534512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21543515205 - 2³ = 21543515197 is a prime.

It is a super-4 number, since 4×21543515205⁴ (a number of 42 digits) contains 4444 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 718117159 + ... + 718117188.

It is an arithmetic number, because the mean of its divisors is an integer number (4308703044).

Almost surely, 2^21543515205 is an apocalyptic number.

It is an amenable number.

21543515205 is a deficient number, since it is larger than the sum of its proper divisors (12926109147).

21543515205 is a wasteful number, since it uses less digits than its factorization.

21543515205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1436234355.

The product of its (nonzero) digits is 30000, while the sum is 33.

The spelling of 21543515205 in words is "twenty-one billion, five hundred forty-three million, five hundred fifteen thousand, two hundred five".