21573507611 has 4 divisors (see below), whose sum is σ = 22708955400. Its totient is φ = 20438059824.

The previous prime is 21573507583. The next prime is 21573507619. The reversal of 21573507611 is 11670537512.

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 21573507611 - 2¹⁸ = 21573245467 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21573507619) 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, 567723866 + ... + 567723903.

It is an arithmetic number, because the mean of its divisors is an integer number (5677238850).

Almost surely, 2^21573507611 is an apocalyptic number.

21573507611 is a deficient number, since it is larger than the sum of its proper divisors (1135447789).

21573507611 is a wasteful number, since it uses less digits than its factorization.

21573507611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1135447788.

The product of its (nonzero) digits is 44100, while the sum is 38.

The spelling of 21573507611 in words is "twenty-one billion, five hundred seventy-three million, five hundred seven thousand, six hundred eleven".