21540302785 has 4 divisors (see below), whose sum is σ = 25848363348. Its totient is φ = 17232242224.

The previous prime is 21540302779. The next prime is 21540302789. The reversal of 21540302785 is 58720304512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16981217344 + 4559085441 = 130312^2 + 67521^2 .

It is a cyclic number.

It is not a de Polignac number, because 21540302785 - 2⁵ = 21540302753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21540302789) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2154030274 + ... + 2154030283.

It is an arithmetic number, because the mean of its divisors is an integer number (6462090837).

Almost surely, 2^21540302785 is an apocalyptic number.

It is an amenable number.

21540302785 is a deficient number, since it is larger than the sum of its proper divisors (4308060563).

21540302785 is an equidigital number, since it uses as much as digits as its factorization.

21540302785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4308060562.

The product of its (nonzero) digits is 67200, while the sum is 37.

The spelling of 21540302785 in words is "twenty-one billion, five hundred forty million, three hundred two thousand, seven hundred eighty-five".