203661 has 16 divisors (see below), whose sum is σ = 318400. Its totient is φ = 128304.

The previous prime is 203659. The next prime is 203663. The reversal of 203661 is 166302.

It is a happy number.

203661 is a `hidden beast` number, since 2 + 0 + 3 + 661 = 666.

It is an interprime number because it is at equal distance from previous prime (203659) and next prime (203663).

It is not a de Polignac number, because 203661 - 2¹ = 203659 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (203663) 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, 315 + ... + 711.

It is an arithmetic number, because the mean of its divisors is an integer number (19900).

2²⁰³⁶⁶¹ is an apocalyptic number.

It is an amenable number.

203661 is a deficient number, since it is larger than the sum of its proper divisors (114739).

203661 is a wasteful number, since it uses less digits than its factorization.

203661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 425 (or 419 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 203661 is about 451.2881562815. The cubic root of 203661 is about 58.8350270270.

Adding to 203661 its reverse (166302), we get a palindrome (369963).

The spelling of 203661 in words is "two hundred three thousand, six hundred sixty-one".