661803281111 has 16 divisors (see below), whose sum is σ = 761362128384. Its totient is φ = 563500196064.

The previous prime is 661803281071. The next prime is 661803281119. The reversal of 661803281111 is 111182308166.

661803281111 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661803281111 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 (661803281119) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4256996 + ... + 4409718.

It is an arithmetic number, because the mean of its divisors is an integer number (47585133024).

Almost surely, 2^661803281111 is an apocalyptic number.

661803281111 is a deficient number, since it is larger than the sum of its proper divisors (99558847273).

661803281111 is a wasteful number, since it uses less digits than its factorization.

661803281111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156830.

The product of its (nonzero) digits is 13824, while the sum is 38.

Adding to 661803281111 its reverse (111182308166), we get a palindrome (772985589277).

The spelling of 661803281111 in words is "six hundred sixty-one billion, eight hundred three million, two hundred eighty-one thousand, one hundred eleven".