6564139961 has 2 divisors, whose sum is σ = 6564139962. Its totient is φ = 6564139960.

The previous prime is 6564139891. The next prime is 6564139997. The reversal of 6564139961 is 1699314656.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4921864336 + 1642275625 = 70156^2 + 40525^2 .

It is a cyclic number.

It is not a de Polignac number, because 6564139961 - 2¹⁰ = 6564138937 is a prime.

It is not a weakly prime, because it can be changed into another prime (6564139661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3282069980 + 3282069981.

It is an arithmetic number, because the mean of its divisors is an integer number (3282069981).

Almost surely, 2^6564139961 is an apocalyptic number.

It is an amenable number.

6564139961 is a deficient number, since it is larger than the sum of its proper divisors (1).

6564139961 is an equidigital number, since it uses as much as digits as its factorization.

6564139961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1049760, while the sum is 50.

The square root of 6564139961 is about 81019.3801568489. The cubic root of 6564139961 is about 1872.3740388459.

The spelling of 6564139961 in words is "six billion, five hundred sixty-four million, one hundred thirty-nine thousand, nine hundred sixty-one".