2645567921 has 4 divisors (see below), whose sum is σ = 2645699700. Its totient is φ = 2645436144.

The previous prime is 2645567887. The next prime is 2645567929. The reversal of 2645567921 is 1297655462.

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 2205617296 + 439950625 = 46964^2 + 20975^2 .

It is a cyclic number.

It is not a de Polignac number, because 2645567921 - 2¹⁴ = 2645551537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2645567929) 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, 28826 + ... + 78243.

It is an arithmetic number, because the mean of its divisors is an integer number (661424925).

Almost surely, 2^2645567921 is an apocalyptic number.

It is an amenable number.

2645567921 is a deficient number, since it is larger than the sum of its proper divisors (131779).

2645567921 is a wasteful number, since it uses less digits than its factorization.

2645567921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131778.

The product of its digits is 907200, while the sum is 47.

The square root of 2645567921 is about 51435.0845338082. The cubic root of 2645567921 is about 1383.0555973248.

The spelling of 2645567921 in words is "two billion, six hundred forty-five million, five hundred sixty-seven thousand, nine hundred twenty-one".