661603 has 2 divisors, whose sum is σ = 661604. Its totient is φ = 661602.

The previous prime is 661553. The next prime is 661607. The reversal of 661603 is 306166.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661603 - 2⁹ = 661091 is a prime.

It is not a weakly prime, because it can be changed into another prime (661607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330801 + 330802.

It is an arithmetic number, because the mean of its divisors is an integer number (330802).

2⁶⁶¹⁶⁰³ is an apocalyptic number.

661603 is a deficient number, since it is larger than the sum of its proper divisors (1).

661603 is an equidigital number, since it uses as much as digits as its factorization.

661603 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 22.

The square root of 661603 is about 813.3898204428. The cubic root of 661603 is about 87.1363081038.

Adding to 661603 its reverse (306166), we get a palindrome (967769).

The spelling of 661603 in words is "six hundred sixty-one thousand, six hundred three".