2565055721 has 4 divisors (see below), whose sum is σ = 2568315792. Its totient is φ = 2561795652.

The previous prime is 2565055709. The next prime is 2565055741. The reversal of 2565055721 is 1275505652.

2565055721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2565055721 - 2²² = 2560861417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2565055741) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1628855 + ... + 1630428.

It is an arithmetic number, because the mean of its divisors is an integer number (642078948).

Almost surely, 2^2565055721 is an apocalyptic number.

It is an amenable number.

2565055721 is a deficient number, since it is larger than the sum of its proper divisors (3260071).

2565055721 is an equidigital number, since it uses as much as digits as its factorization.

2565055721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3260070.

The product of its (nonzero) digits is 105000, while the sum is 38.

The square root of 2565055721 is about 50646.3791499452. The cubic root of 2565055721 is about 1368.8807028054.

The spelling of 2565055721 in words is "two billion, five hundred sixty-five million, fifty-five thousand, seven hundred twenty-one".