661003663 has 2 divisors, whose sum is σ = 661003664. Its totient is φ = 661003662.

The previous prime is 661003657. The next prime is 661003769. The reversal of 661003663 is 366300166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 661003663 - 2⁹ = 661003151 is a prime.

661003663 is a modest number, since divided by 3663 gives 661 as remainder.

It is equal to p_34335643 and since 661003663 and 34335643 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661013663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330501831 + 330501832.

It is an arithmetic number, because the mean of its divisors is an integer number (330501832).

Almost surely, 2^661003663 is an apocalyptic number.

661003663 is a deficient number, since it is larger than the sum of its proper divisors (1).

661003663 is an equidigital number, since it uses as much as digits as its factorization.

661003663 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11664, while the sum is 31.

The square root of 661003663 is about 25709.9915013599. The cubic root of 661003663 is about 871.0998829618.

The spelling of 661003663 in words is "six hundred sixty-one million, three thousand, six hundred sixty-three".