661917 has 16 divisors (see below), whose sum is σ = 943488. Its totient is φ = 411840.

The previous prime is 661909. The next prime is 661931. The reversal of 661917 is 719166.

661917 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 661917 - 2³ = 661909 is a prime.

It is a super-2 number, since 2×661917² = 876268229778, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661987) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3567 + ... + 3747.

It is an arithmetic number, because the mean of its divisors is an integer number (58968).

2⁶⁶¹⁹¹⁷ is an apocalyptic number.

It is an amenable number.

661917 is a deficient number, since it is larger than the sum of its proper divisors (281571).

661917 is a wasteful number, since it uses less digits than its factorization.

661917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 260.

The product of its digits is 2268, while the sum is 30.

The square root of 661917 is about 813.5828169277. The cubic root of 661917 is about 87.1500910287.

The spelling of 661917 in words is "six hundred sixty-one thousand, nine hundred seventeen".