663606021 has 16 divisors (see below), whose sum is σ = 953334144. Its totient is φ = 408174144.

The previous prime is 663605993. The next prime is 663606023. The reversal of 663606021 is 120606366.

663606021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 663606021 - 2⁷ = 663605893 is a prime.

It is a super-2 number, since 2×663606021² = 880745902214904882, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 663606021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (663606023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 144655 + ... + 149171.

It is an arithmetic number, because the mean of its divisors is an integer number (59583384).

Almost surely, 2^663606021 is an apocalyptic number.

It is an amenable number.

663606021 is a deficient number, since it is larger than the sum of its proper divisors (289728123).

663606021 is a wasteful number, since it uses less digits than its factorization.

663606021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8300.

The product of its (nonzero) digits is 7776, while the sum is 30.

The square root of 663606021 is about 25760.5516439381. The cubic root of 663606021 is about 872.2415535428.

The spelling of 663606021 in words is "six hundred sixty-three million, six hundred six thousand, twenty-one".