21313265561 has 8 divisors (see below), whose sum is σ = 25640018880. Its totient is φ = 17307012528.

The previous prime is 21313265549. The next prime is 21313265581. The reversal of 21313265561 is 16556231312.

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

It is a cyclic number.

It is not a de Polignac number, because 21313265561 - 2¹⁰ = 21313264537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21313265581) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 80124926 + ... + 80125191.

It is an arithmetic number, because the mean of its divisors is an integer number (3205002360).

Almost surely, 2^21313265561 is an apocalyptic number.

It is an amenable number.

21313265561 is a deficient number, since it is larger than the sum of its proper divisors (4326753319).

21313265561 is a wasteful number, since it uses less digits than its factorization.

21313265561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160250143.

The product of its digits is 32400, while the sum is 35.

Adding to 21313265561 its reverse (16556231312), we get a palindrome (37869496873).

The spelling of 21313265561 in words is "twenty-one billion, three hundred thirteen million, two hundred sixty-five thousand, five hundred sixty-one".