20863645 has 16 divisors (see below), whose sum is σ = 28501632. Its totient is φ = 14512960.

The previous prime is 20863637. The next prime is 20863649. The reversal of 20863645 is 54636802.

It is a happy number.

It is not a de Polignac number, because 20863645 - 2³ = 20863637 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 20863645.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20863649) 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, 6982 + ... + 9511.

It is an arithmetic number, because the mean of its divisors is an integer number (1781352).

Almost surely, 2^20863645 is an apocalyptic number.

It is an amenable number.

20863645 is a deficient number, since it is larger than the sum of its proper divisors (7637987).

20863645 is a wasteful number, since it uses less digits than its factorization.

20863645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16532.

The product of its (nonzero) digits is 34560, while the sum is 34.

The square root of 20863645 is about 4567.6739156818. The cubic root of 20863645 is about 275.2939886299.

The spelling of 20863645 in words is "twenty million, eight hundred sixty-three thousand, six hundred forty-five".