2645251721 has 12 divisors (see below), whose sum is σ = 3116085120. Its totient is φ = 2238654600.

The previous prime is 2645251717. The next prime is 2645251751. The reversal of 2645251721 is 1271525462.

It is not a de Polignac number, because 2645251721 - 2² = 2645251717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2645251751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 337805 + ... + 345546.

It is an arithmetic number, because the mean of its divisors is an integer number (259673760).

Almost surely, 2^2645251721 is an apocalyptic number.

It is an amenable number.

2645251721 is a deficient number, since it is larger than the sum of its proper divisors (470833399).

2645251721 is an equidigital number, since it uses as much as digits as its factorization.

2645251721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 683444 (or 683437 counting only the distinct ones).

The product of its digits is 33600, while the sum is 35.

The square root of 2645251721 is about 51432.0106645657. The cubic root of 2645251721 is about 1383.0004938944. Note that the first 3 decimals are identical.

The spelling of 2645251721 in words is "two billion, six hundred forty-five million, two hundred fifty-one thousand, seven hundred twenty-one".