21270500765 has 4 divisors (see below), whose sum is σ = 25524600924. Its totient is φ = 17016400608.

The previous prime is 21270500749. The next prime is 21270500813. The reversal of 21270500765 is 56700507212.

It is a happy number.

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 13336323289 + 7934177476 = 115483^2 + 89074^2 .

It is a cyclic number.

It is not a de Polignac number, because 21270500765 - 2⁴ = 21270500749 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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, 2127050072 + ... + 2127050081.

It is an arithmetic number, because the mean of its divisors is an integer number (6381150231).

Almost surely, 2^21270500765 is an apocalyptic number.

It is an amenable number.

21270500765 is a deficient number, since it is larger than the sum of its proper divisors (4254100159).

21270500765 is an equidigital number, since it uses as much as digits as its factorization.

21270500765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4254100158.

The product of its (nonzero) digits is 29400, while the sum is 35.

The spelling of 21270500765 in words is "twenty-one billion, two hundred seventy million, five hundred thousand, seven hundred sixty-five".