581533386661 has 4 divisors (see below), whose sum is σ = 591389884800. Its totient is φ = 571676888524.

The previous prime is 581533386649. The next prime is 581533386671. The reversal of 581533386661 is 166683335185.

581533386661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 581533386661 - 2¹⁵ = 581533353893 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (581533386671) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4928248981 + ... + 4928249098.

It is an arithmetic number, because the mean of its divisors is an integer number (147847471200).

Almost surely, 2^581533386661 is an apocalyptic number.

It is an amenable number.

581533386661 is a deficient number, since it is larger than the sum of its proper divisors (9856498139).

581533386661 is an equidigital number, since it uses as much as digits as its factorization.

581533386661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9856498138.

The product of its digits is 9331200, while the sum is 55.

The spelling of 581533386661 in words is "five hundred eighty-one billion, five hundred thirty-three million, three hundred eighty-six thousand, six hundred sixty-one".