21909728635 has 4 divisors (see below), whose sum is σ = 26291674368. Its totient is φ = 17527782904.

The previous prime is 21909728567. The next prime is 21909728651. The reversal of 21909728635 is 53682790912.

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 21909728635 - 2²⁷ = 21775510907 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2190972859 + ... + 2190972868.

It is an arithmetic number, because the mean of its divisors is an integer number (6572918592).

Almost surely, 2^21909728635 is an apocalyptic number.

21909728635 is a deficient number, since it is larger than the sum of its proper divisors (4381945733).

21909728635 is an equidigital number, since it uses as much as digits as its factorization.

21909728635 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4381945732.

The product of its (nonzero) digits is 1632960, while the sum is 52.

The spelling of 21909728635 in words is "twenty-one billion, nine hundred nine million, seven hundred twenty-eight thousand, six hundred thirty-five".