661403 has 4 divisors (see below), whose sum is σ = 684240. Its totient is φ = 638568.

The previous prime is 661393. The next prime is 661417. The reversal of 661403 is 304166.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 304166 = 2 ⋅152083.

It is a cyclic number.

It is not a de Polignac number, because 661403 - 2¹⁰ = 660379 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 661403.

It is not an unprimeable number, because it can be changed into a prime (661483) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11375 + ... + 11432.

It is an arithmetic number, because the mean of its divisors is an integer number (171060).

2⁶⁶¹⁴⁰³ is an apocalyptic number.

661403 is a deficient number, since it is larger than the sum of its proper divisors (22837).

661403 is a wasteful number, since it uses less digits than its factorization.

661403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22836.

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

The square root of 661403 is about 813.2668688690. The cubic root of 661403 is about 87.1275268972.

Adding to 661403 its reverse (304166), we get a palindrome (965569).

The spelling of 661403 in words is "six hundred sixty-one thousand, four hundred three".