6561046621 has 2 divisors, whose sum is σ = 6561046622. Its totient is φ = 6561046620.

The previous prime is 6561046619. The next prime is 6561046669. The reversal of 6561046621 is 1266401656.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5014197721 + 1546848900 = 70811^2 + 39330^2 .

It is a cyclic number.

It is not a de Polignac number, because 6561046621 - 2¹ = 6561046619 is a prime.

Together with 6561046619, 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 (6561046421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3280523310 + 3280523311.

It is an arithmetic number, because the mean of its divisors is an integer number (3280523311).

Almost surely, 2^6561046621 is an apocalyptic number.

It is an amenable number.

6561046621 is a deficient number, since it is larger than the sum of its proper divisors (1).

6561046621 is an equidigital number, since it uses as much as digits as its factorization.

6561046621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 51840, while the sum is 37.

The square root of 6561046621 is about 81000.2877834394. The cubic root of 6561046621 is about 1872.0798749195.

The spelling of 6561046621 in words is "six billion, five hundred sixty-one million, forty-six thousand, six hundred twenty-one".