661356611 has 4 divisors (see below), whose sum is σ = 679231152. Its totient is φ = 643482072.

The previous prime is 661356589. The next prime is 661356659. The reversal of 661356611 is 116653166.

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 661356611 - 2¹⁰ = 661355587 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661356911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8937215 + ... + 8937288.

It is an arithmetic number, because the mean of its divisors is an integer number (169807788).

Almost surely, 2^661356611 is an apocalyptic number.

661356611 is a deficient number, since it is larger than the sum of its proper divisors (17874541).

661356611 is a wasteful number, since it uses less digits than its factorization.

661356611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17874540.

The product of its digits is 19440, while the sum is 35.

The square root of 661356611 is about 25716.8546093802. The cubic root of 661356611 is about 871.2548988731.

The spelling of 661356611 in words is "six hundred sixty-one million, three hundred fifty-six thousand, six hundred eleven".