20643136 has 14 divisors (see below), whose sum is σ = 40963850. Its totient is φ = 10321536.

The previous prime is 20643127. The next prime is 20643137. The reversal of 20643136 is 63134602.

It can be written as a sum of positive squares in only one way, i.e., 10758400 + 9884736 = 3280^2 + 3144^2 .

It is a super-2 number, since 2×20643136² = 852278127828992, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20643136.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20643137) 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 as a sum of consecutive naturals, namely, 161211 + ... + 161338.

Almost surely, 2^20643136 is an apocalyptic number.

It is an amenable number.

20643136 is a deficient number, since it is larger than the sum of its proper divisors (20320714).

20643136 is an equidigital number, since it uses as much as digits as its factorization.

20643136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322561 (or 322551 counting only the distinct ones).

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

The square root of 20643136 is about 4543.4718002866. The cubic root of 20643136 is about 274.3206858518.

Adding to 20643136 its reverse (63134602), we get a palindrome (83777738).

The spelling of 20643136 in words is "twenty million, six hundred forty-three thousand, one hundred thirty-six".