20643471 has 16 divisors (see below), whose sum is σ = 30750720. Its totient is φ = 13686840.

The previous prime is 20643449. The next prime is 20643487. The reversal of 20643471 is 17434602.

It is not a de Polignac number, because 20643471 - 2⁵ = 20643439 is a prime.

It is a super-3 number, since 3×20643471³ (a number of 23 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20643421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3156 + ... + 7158.

It is an arithmetic number, because the mean of its divisors is an integer number (1921920).

Almost surely, 2^20643471 is an apocalyptic number.

20643471 is a deficient number, since it is larger than the sum of its proper divisors (10107249).

20643471 is a wasteful number, since it uses less digits than its factorization.

20643471 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4203 (or 4197 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 27.

The square root of 20643471 is about 4543.5086662182. The cubic root of 20643471 is about 274.3221697499.

The spelling of 20643471 in words is "twenty million, six hundred forty-three thousand, four hundred seventy-one".