661633764205 has 16 divisors (see below), whose sum is σ = 845817174720. Its totient is φ = 495407190528.

The previous prime is 661633764173. The next prime is 661633764227. The reversal of 661633764205 is 502467336166.

It is a cyclic number.

It is not a de Polignac number, because 661633764205 - 2⁵ = 661633764173 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41947332 + ... + 41963101.

It is an arithmetic number, because the mean of its divisors is an integer number (52863573420).

Almost surely, 2^661633764205 is an apocalyptic number.

It is an amenable number.

661633764205 is a deficient number, since it is larger than the sum of its proper divisors (184183410515).

661633764205 is a wasteful number, since it uses less digits than its factorization.

661633764205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83910540.

The product of its (nonzero) digits is 3265920, while the sum is 49.

The spelling of 661633764205 in words is "six hundred sixty-one billion, six hundred thirty-three million, seven hundred sixty-four thousand, two hundred five".