2645661521 has 4 divisors (see below), whose sum is σ = 2659513344. Its totient is φ = 2631809700.

The previous prime is 2645661463. The next prime is 2645661523. The reversal of 2645661521 is 1251665462.

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 2645661521 - 2²² = 2641467217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2645661523) 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 3 ways as a sum of consecutive naturals, for example, 6925625 + ... + 6926006.

It is an arithmetic number, because the mean of its divisors is an integer number (664878336).

Almost surely, 2^2645661521 is an apocalyptic number.

It is an amenable number.

2645661521 is a deficient number, since it is larger than the sum of its proper divisors (13851823).

2645661521 is a wasteful number, since it uses less digits than its factorization.

2645661521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13851822.

The product of its digits is 86400, while the sum is 38.

The square root of 2645661521 is about 51435.9944105293. The cubic root of 2645661521 is about 1383.0719079345.

The spelling of 2645661521 in words is "two billion, six hundred forty-five million, six hundred sixty-one thousand, five hundred twenty-one".