663814021 has 4 divisors (see below), whose sum is σ = 714876652. Its totient is φ = 612751392.

The previous prime is 663814013. The next prime is 663814049. The reversal of 663814021 is 120418366.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 106193025 + 557620996 = 10305^2 + 23614^2 .

It is a cyclic number.

It is not a de Polignac number, because 663814021 - 2³ = 663814013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (663884021) 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 in 3 ways as a sum of consecutive naturals, for example, 25531296 + ... + 25531321.

It is an arithmetic number, because the mean of its divisors is an integer number (178719163).

Almost surely, 2^663814021 is an apocalyptic number.

It is an amenable number.

663814021 is a deficient number, since it is larger than the sum of its proper divisors (51062631).

663814021 is a wasteful number, since it uses less digits than its factorization.

663814021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51062630.

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 663814021 is about 25764.5885082607. The cubic root of 663814021 is about 872.3326755265.

The spelling of 663814021 in words is "six hundred sixty-three million, eight hundred fourteen thousand, twenty-one".