661765603 has 4 divisors (see below), whose sum is σ = 662893560. Its totient is φ = 660637648.

The previous prime is 661765583. The next prime is 661765607. The reversal of 661765603 is 306567166.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661765603 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661765607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 563098 + ... + 564271.

It is an arithmetic number, because the mean of its divisors is an integer number (165723390).

Almost surely, 2^661765603 is an apocalyptic number.

661765603 is a deficient number, since it is larger than the sum of its proper divisors (1127957).

661765603 is a wasteful number, since it uses less digits than its factorization.

661765603 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1127956.

The product of its (nonzero) digits is 136080, while the sum is 40.

The square root of 661765603 is about 25724.8052082032. The cubic root of 661765603 is about 871.4344605238.

The spelling of 661765603 in words is "six hundred sixty-one million, seven hundred sixty-five thousand, six hundred three".