661665017 has 8 divisors (see below), whose sum is σ = 712831560. Its totient is φ = 610536960.

The previous prime is 661664981. The next prime is 661665029. The reversal of 661665017 is 710566166.

It can be written as a sum of positive squares in 4 ways, for example, as 712336 + 660952681 = 844^2 + 25709^2 .

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 661665017 - 2⁶ = 661664953 is a prime.

It is a super-2 number, since 2×661665017² = 875601189443220578, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661665077) 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, 33167 + ... + 49227.

It is an arithmetic number, because the mean of its divisors is an integer number (89103945).

Almost surely, 2^661665017 is an apocalyptic number.

It is an amenable number.

661665017 is a deficient number, since it is larger than the sum of its proper divisors (51166543).

661665017 is a wasteful number, since it uses less digits than its factorization.

661665017 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19243.

The product of its (nonzero) digits is 45360, while the sum is 38.

The square root of 661665017 is about 25722.8500948087. The cubic root of 661665017 is about 871.3903066483.

The spelling of 661665017 in words is "six hundred sixty-one million, six hundred sixty-five thousand, seventeen".