661322611 has 4 divisors (see below), whose sum is σ = 690075792. Its totient is φ = 632569432.

The previous prime is 661322609. The next prime is 661322647. The reversal of 661322611 is 116223166.

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

It is a cyclic number.

It is not a de Polignac number, because 661322611 - 2¹ = 661322609 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 661322611.

It is not an unprimeable number, because it can be changed into a prime (661352611) 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, 14376556 + ... + 14376601.

It is an arithmetic number, because the mean of its divisors is an integer number (172518948).

Almost surely, 2^661322611 is an apocalyptic number.

661322611 is a deficient number, since it is larger than the sum of its proper divisors (28753181).

661322611 is a wasteful number, since it uses less digits than its factorization.

661322611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28753180.

The product of its digits is 2592, while the sum is 28.

The square root of 661322611 is about 25716.1935558123. The cubic root of 661322611 is about 871.2399683632.

Adding to 661322611 its reverse (116223166), we get a palindrome (777545777).

The spelling of 661322611 in words is "six hundred sixty-one million, three hundred twenty-two thousand, six hundred eleven".