66821603 has 4 divisors (see below), whose sum is σ = 66837960. Its totient is φ = 66805248.

The previous prime is 66821591. The next prime is 66821621. The reversal of 66821603 is 30612866.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 66821603 - 2¹⁸ = 66559459 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66821603.

It is not an unprimeable number, because it can be changed into a prime (66821683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3728 + ... + 12146.

It is an arithmetic number, because the mean of its divisors is an integer number (16709490).

Almost surely, 2^66821603 is an apocalyptic number.

66821603 is a deficient number, since it is larger than the sum of its proper divisors (16357).

66821603 is an equidigital number, since it uses as much as digits as its factorization.

66821603 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16356.

The product of its (nonzero) digits is 10368, while the sum is 32.

The square root of 66821603 is about 8174.4481770943. The cubic root of 66821603 is about 405.7940080357.

The spelling of 66821603 in words is "sixty-six million, eight hundred twenty-one thousand, six hundred three".