661305 has 8 divisors (see below), whose sum is σ = 1058112. Its totient is φ = 352688.

The previous prime is 661267. The next prime is 661321. The reversal of 661305 is 503166.

661305 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 661305 - 2⁸ = 661049 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22029 + ... + 22058.

It is an arithmetic number, because the mean of its divisors is an integer number (132264).

2⁶⁶¹³⁰⁵ is an apocalyptic number.

It is an amenable number.

661305 is a deficient number, since it is larger than the sum of its proper divisors (396807).

661305 is a wasteful number, since it uses less digits than its factorization.

661305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44095.

The product of its (nonzero) digits is 540, while the sum is 21.

The square root of 661305 is about 813.2066158118. The cubic root of 661305 is about 87.1232234597.

The spelling of 661305 in words is "six hundred sixty-one thousand, three hundred five".