21540730065 has 32 divisors (see below), whose sum is σ = 36357703680. Its totient is φ = 10860163776.

The previous prime is 21540730049. The next prime is 21540730069. The reversal of 21540730065 is 56003704512.

It is not a de Polignac number, because 21540730065 - 2⁴ = 21540730049 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21540730069) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 50334 + ... + 213576.

It is an arithmetic number, because the mean of its divisors is an integer number (1136178240).

Almost surely, 2^21540730065 is an apocalyptic number.

It is an amenable number.

21540730065 is a deficient number, since it is larger than the sum of its proper divisors (14816973615).

21540730065 is a wasteful number, since it uses less digits than its factorization.

21540730065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163733.

The product of its (nonzero) digits is 25200, while the sum is 33.

The spelling of 21540730065 in words is "twenty-one billion, five hundred forty million, seven hundred thirty thousand, sixty-five".