20643361 has 4 divisors (see below), whose sum is σ = 20780224. Its totient is φ = 20506500.

The previous prime is 20643353. The next prime is 20643379. The reversal of 20643361 is 16334602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20643361 - 2³ = 20643353 is a prime.

It is a super-2 number, since 2×20643361² = 852296706752642, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20643061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 68205 + ... + 68506.

It is an arithmetic number, because the mean of its divisors is an integer number (5195056).

Almost surely, 2^20643361 is an apocalyptic number.

It is an amenable number.

20643361 is a deficient number, since it is larger than the sum of its proper divisors (136863).

20643361 is a wasteful number, since it uses less digits than its factorization.

20643361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136862.

The product of its (nonzero) digits is 2592, while the sum is 25.

The square root of 20643361 is about 4543.4965610199. The cubic root of 20643361 is about 274.3216825015.

Adding to 20643361 its reverse (16334602), we get a palindrome (36977963).

The spelling of 20643361 in words is "twenty million, six hundred forty-three thousand, three hundred sixty-one".