663181 has 4 divisors (see below), whose sum is σ = 664864. Its totient is φ = 661500.

The previous prime is 663167. The next prime is 663191. The reversal of 663181 is 181366.

663181 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a 3-Lehmer number, since φ(663181) divides (663181-1)³.

It is a cyclic number.

It is not a de Polignac number, because 663181 - 2⁵ = 663149 is a prime.

It is a super-2 number, since 2×663181² = 879618077522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (663161) 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, 106 + ... + 1156.

It is an arithmetic number, because the mean of its divisors is an integer number (166216).

2⁶⁶³¹⁸¹ is an apocalyptic number.

It is an amenable number.

663181 is a deficient number, since it is larger than the sum of its proper divisors (1683).

663181 is a wasteful number, since it uses less digits than its factorization.

663181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1682.

The product of its digits is 864, while the sum is 25.

The square root of 663181 is about 814.3592573306. The cubic root of 663181 is about 87.2055298376.

The spelling of 663181 in words is "six hundred sixty-three thousand, one hundred eighty-one".