661863 has 8 divisors (see below), whose sum is σ = 904176. Its totient is φ = 430400.

The previous prime is 661849. The next prime is 661873. The reversal of 661863 is 368166.

661863 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 661863 - 2⁸ = 661607 is a prime.

661863 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 661863.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661823) 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, 2568 + ... + 2813.

It is an arithmetic number, because the mean of its divisors is an integer number (113022).

2⁶⁶¹⁸⁶³ is an apocalyptic number.

661863 is a deficient number, since it is larger than the sum of its proper divisors (242313).

661863 is a wasteful number, since it uses less digits than its factorization.

661863 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5425.

The product of its digits is 5184, while the sum is 30.

The square root of 661863 is about 813.5496297092. The cubic root of 661863 is about 87.1477210272.

The spelling of 661863 in words is "six hundred sixty-one thousand, eight hundred sixty-three".