21753540809 has 24 divisors (see below), whose sum is σ = 29428835520. Its totient is φ = 15646894560.

The previous prime is 21753540793. The next prime is 21753540811. The reversal of 21753540809 is 90804535712.

It is not a de Polignac number, because 21753540809 - 2⁴ = 21753540793 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21753540809.

It is not an unprimeable number, because it can be changed into a prime (21753540899) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 976799 + ... + 998820.

It is an arithmetic number, because the mean of its divisors is an integer number (1226201480).

Almost surely, 2^21753540809 is an apocalyptic number.

It is an amenable number.

21753540809 is a deficient number, since it is larger than the sum of its proper divisors (7675294711).

21753540809 is a wasteful number, since it uses less digits than its factorization.

21753540809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1975661 (or 1975650 counting only the distinct ones).

The product of its (nonzero) digits is 302400, while the sum is 44.

The spelling of 21753540809 in words is "twenty-one billion, seven hundred fifty-three million, five hundred forty thousand, eight hundred nine".