219661 has 8 divisors (see below), whose sum is σ = 241304. Its totient is φ = 198720.

The previous prime is 219649. The next prime is 219677. The reversal of 219661 is 166912.

219661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 17161 + 202500 = 131^2 + 450^2 .

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 219661 - 2⁵ = 219629 is a prime.

It is a Duffinian number.

219661 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (219361) by changing a digit.

It is a nontrivial repunit in base 60.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 655 + ... + 931.

It is an arithmetic number, because the mean of its divisors is an integer number (30163).

2²¹⁹⁶⁶¹ is an apocalyptic number.

It is an amenable number.

219661 is a deficient number, since it is larger than the sum of its proper divisors (21643).

219661 is a wasteful number, since it uses less digits than its factorization.

219661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 351.

The product of its digits is 648, while the sum is 25.

The square root of 219661 is about 468.6800614492. The cubic root of 219661 is about 60.3370841727.

It can be divided in two parts, 2196 and 61, that multiplied together give a square (133956 = 366²).

The spelling of 219661 in words is "two hundred nineteen thousand, six hundred sixty-one".