660380561 has 4 divisors (see below), whose sum is σ = 660515124. Its totient is φ = 660246000.

The previous prime is 660380537. The next prime is 660380593. The reversal of 660380561 is 165083066.

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

It can be written as a sum of positive squares in 2 ways, for example, as 22515025 + 637865536 = 4745^2 + 25256^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-660380561 is a prime.

It is a super-2 number, since 2×660380561² = 872204970693349442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (660383561) 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, 59630 + ... + 69831.

It is an arithmetic number, because the mean of its divisors is an integer number (165128781).

Almost surely, 2^660380561 is an apocalyptic number.

It is an amenable number.

660380561 is a deficient number, since it is larger than the sum of its proper divisors (134563).

660380561 is a wasteful number, since it uses less digits than its factorization.

660380561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134562.

The product of its (nonzero) digits is 25920, while the sum is 35.

The square root of 660380561 is about 25697.8707483714. The cubic root of 660380561 is about 870.8260797780.

The spelling of 660380561 in words is "six hundred sixty million, three hundred eighty thousand, five hundred sixty-one".