661318563 has 8 divisors (see below), whose sum is σ = 920095488. Its totient is φ = 421710344.

The previous prime is 661318481. The next prime is 661318573. The reversal of 661318563 is 365813166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 661318563 - 2¹⁴ = 661302179 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661318573) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4792095 + ... + 4792232.

It is an arithmetic number, because the mean of its divisors is an integer number (115011936).

Almost surely, 2^661318563 is an apocalyptic number.

661318563 is a deficient number, since it is larger than the sum of its proper divisors (258776925).

661318563 is a wasteful number, since it uses less digits than its factorization.

661318563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9584353.

The product of its digits is 77760, while the sum is 39.

The square root of 661318563 is about 25716.1148504202. The cubic root of 661318563 is about 871.2381907202.

The spelling of 661318563 in words is "six hundred sixty-one million, three hundred eighteen thousand, five hundred sixty-three".