661361351240563 has 4 divisors (see below), whose sum is σ = 671232416184520. Its totient is φ = 651490286296608.

The previous prime is 661361351240561. The next prime is 661361351240587. The reversal of 661361351240563 is 365042153163166.

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 661361351240563 - 2¹ = 661361351240561 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 661361351240563.

It is not an unprimeable number, because it can be changed into a prime (661361351240561) 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, 4935532471878 + ... + 4935532472011.

It is an arithmetic number, because the mean of its divisors is an integer number (167808104046130).

Almost surely, 2^{661361351240563} is an apocalyptic number.

661361351240563 is a deficient number, since it is larger than the sum of its proper divisors (9871064943957).

661361351240563 is an equidigital number, since it uses as much as digits as its factorization.

661361351240563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9871064943956.

The product of its (nonzero) digits is 6998400, while the sum is 52.

The spelling of 661361351240563 in words is "six hundred sixty-one trillion, three hundred sixty-one billion, three hundred fifty-one million, two hundred forty thousand, five hundred sixty-three".