661612011205 has 4 divisors (see below), whose sum is σ = 793934413452. Its totient is φ = 529289608960.

The previous prime is 661612011169. The next prime is 661612011209. The reversal of 661612011205 is 502110216166.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 457385747809 + 204226263396 = 676303^2 + 451914^2 .

It is not a de Polignac number, because 661612011205 - 2⁹ = 661612010693 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661612011209) 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, 66161201116 + ... + 66161201125.

It is an arithmetic number, because the mean of its divisors is an integer number (198483603363).

Almost surely, 2^661612011205 is an apocalyptic number.

It is an amenable number.

661612011205 is a deficient number, since it is larger than the sum of its proper divisors (132322402247).

661612011205 is a wasteful number, since it uses less digits than its factorization.

661612011205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132322402246.

The product of its (nonzero) digits is 4320, while the sum is 31.

The spelling of 661612011205 in words is "six hundred sixty-one billion, six hundred twelve million, eleven thousand, two hundred five".