403661 has 2 divisors, whose sum is σ = 403662. Its totient is φ = 403660.

The previous prime is 403649. The next prime is 403679. The reversal of 403661 is 166304.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 366025 + 37636 = 605^2 + 194^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-403661 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (403621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 201830 + 201831.

It is an arithmetic number, because the mean of its divisors is an integer number (201831).

2⁴⁰³⁶⁶¹ is an apocalyptic number.

It is an amenable number.

403661 is a deficient number, since it is larger than the sum of its proper divisors (1).

403661 is an equidigital number, since it uses as much as digits as its factorization.

403661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 20.

The square root of 403661 is about 635.3432143338. The cubic root of 403661 is about 73.9047349720.

Adding to 403661 its reverse (166304), we get a palindrome (569965).

The spelling of 403661 in words is "four hundred three thousand, six hundred sixty-one".