6656877581 has 2 divisors, whose sum is σ = 6656877582. Its totient is φ = 6656877580.

The previous prime is 6656877541. The next prime is 6656877589. The reversal of 6656877581 is 1857786566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6433644100 + 223233481 = 80210^2 + 14941^2 .

It is a cyclic number.

It is not a de Polignac number, because 6656877581 - 2⁶ = 6656877517 is a prime.

It is a super-2 number, since 2×6656877581² = 88628038256840823122, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 6656877581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6656877589) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3328438790 + 3328438791.

It is an arithmetic number, because the mean of its divisors is an integer number (3328438791).

Almost surely, 2^6656877581 is an apocalyptic number.

It is an amenable number.

6656877581 is a deficient number, since it is larger than the sum of its proper divisors (1).

6656877581 is an equidigital number, since it uses as much as digits as its factorization.

6656877581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16934400, while the sum is 59.

The square root of 6656877581 is about 81589.6904087765. The cubic root of 6656877581 is about 1881.1504182841.

The spelling of 6656877581 in words is "six billion, six hundred fifty-six million, eight hundred seventy-seven thousand, five hundred eighty-one".