661560571 has 4 divisors (see below), whose sum is σ = 756069232. Its totient is φ = 567051912.

The previous prime is 661560541. The next prime is 661560607. The reversal of 661560571 is 175065166.

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

It is not a de Polignac number, because 661560571 - 2⁵ = 661560539 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 661560571.

It is not an unprimeable number, because it can be changed into a prime (661560521) 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, 47254320 + ... + 47254333.

It is an arithmetic number, because the mean of its divisors is an integer number (189017308).

Almost surely, 2^661560571 is an apocalyptic number.

661560571 is a deficient number, since it is larger than the sum of its proper divisors (94508661).

661560571 is an equidigital number, since it uses as much as digits as its factorization.

661560571 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94508660.

The product of its (nonzero) digits is 37800, while the sum is 37.

The square root of 661560571 is about 25720.8197964217. The cubic root of 661560571 is about 871.3444536266.

The spelling of 661560571 in words is "six hundred sixty-one million, five hundred sixty thousand, five hundred seventy-one".