20644663 has 4 divisors (see below), whose sum is σ = 22232728. Its totient is φ = 19056600.

The previous prime is 20644649. The next prime is 20644693. The reversal of 20644663 is 36644602.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20644663 is a prime.

It is a super-2 number, since 2×20644663² = 852404220767138, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20644633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 794013 + ... + 794038.

It is an arithmetic number, because the mean of its divisors is an integer number (5558182).

Almost surely, 2^20644663 is an apocalyptic number.

20644663 is a deficient number, since it is larger than the sum of its proper divisors (1588065).

20644663 is a wasteful number, since it uses less digits than its factorization.

20644663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1588064.

The product of its (nonzero) digits is 20736, while the sum is 31.

The square root of 20644663 is about 4543.6398404803. The cubic root of 20644663 is about 274.3274496393.

The spelling of 20644663 in words is "twenty million, six hundred forty-four thousand, six hundred sixty-three".