2656660621 has 2 divisors, whose sum is σ = 2656660622. Its totient is φ = 2656660620.

The previous prime is 2656660619. The next prime is 2656660631. The reversal of 2656660621 is 1260666562.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1680098121 + 976562500 = 40989^2 + 31250^2 .

It is a cyclic number.

It is not a de Polignac number, because 2656660621 - 2¹ = 2656660619 is a prime.

Together with 2656660619, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2656660631) 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 as a sum of consecutive naturals, namely, 1328330310 + 1328330311.

It is an arithmetic number, because the mean of its divisors is an integer number (1328330311).

Almost surely, 2^2656660621 is an apocalyptic number.

It is an amenable number.

2656660621 is a deficient number, since it is larger than the sum of its proper divisors (1).

2656660621 is an equidigital number, since it uses as much as digits as its factorization.

2656660621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 155520, while the sum is 40.

The square root of 2656660621 is about 51542.8037751149. The cubic root of 2656660621 is about 1384.9859236493.

The spelling of 2656660621 in words is "two billion, six hundred fifty-six million, six hundred sixty thousand, six hundred twenty-one".