20663645 has 8 divisors (see below), whose sum is σ = 24876504. Its totient is φ = 16477504.

The previous prime is 20663633. The next prime is 20663651. The reversal of 20663645 is 54636602.

It can be written as a sum of positive squares in 4 ways, for example, as 395641 + 20268004 = 629^2 + 4502^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20663645 - 2¹² = 20659549 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4934 + ... + 8103.

It is an arithmetic number, because the mean of its divisors is an integer number (3109563).

Almost surely, 2^20663645 is an apocalyptic number.

It is an amenable number.

20663645 is a deficient number, since it is larger than the sum of its proper divisors (4212859).

20663645 is a wasteful number, since it uses less digits than its factorization.

20663645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13359.

The product of its (nonzero) digits is 25920, while the sum is 32.

The square root of 20663645 is about 4545.7282144889. The cubic root of 20663645 is about 274.4115018468.

The spelling of 20663645 in words is "twenty million, six hundred sixty-three thousand, six hundred forty-five".