20864921 has 8 divisors (see below), whose sum is σ = 26013504. Its totient is φ = 16258320.

The previous prime is 20864863. The next prime is 20864923. The reversal of 20864921 is 12946802.

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 20864921 - 2¹⁰ = 20863897 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20864923) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 135410 + ... + 135563.

It is an arithmetic number, because the mean of its divisors is an integer number (3251688).

Almost surely, 2^20864921 is an apocalyptic number.

It is an amenable number.

20864921 is a deficient number, since it is larger than the sum of its proper divisors (5148583).

20864921 is a wasteful number, since it uses less digits than its factorization.

20864921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 270991.

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 20864921 is about 4567.8135907675. The cubic root of 20864921 is about 275.2996007520.

It can be divided in two parts, 2086 and 4921, that added together give a palindrome (7007).

The spelling of 20864921 in words is "twenty million, eight hundred sixty-four thousand, nine hundred twenty-one".