6655721591 has 2 divisors, whose sum is σ = 6655721592. Its totient is φ = 6655721590.

The previous prime is 6655721551. The next prime is 6655721617. The reversal of 6655721591 is 1951275566.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 6655721591 - 2¹⁰ = 6655720567 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6655721521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3327860795 + 3327860796.

It is an arithmetic number, because the mean of its divisors is an integer number (3327860796).

Almost surely, 2^6655721591 is an apocalyptic number.

6655721591 is a deficient number, since it is larger than the sum of its proper divisors (1).

6655721591 is an equidigital number, since it uses as much as digits as its factorization.

6655721591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 567000, while the sum is 47.

The square root of 6655721591 is about 81582.6059341083. The cubic root of 6655721591 is about 1881.0415225377.

The spelling of 6655721591 in words is "six billion, six hundred fifty-five million, seven hundred twenty-one thousand, five hundred ninety-one".