20871541 has 4 divisors (see below), whose sum is σ = 20880684. Its totient is φ = 20862400.

The previous prime is 20871509. The next prime is 20871551. The reversal of 20871541 is 14517802.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 14516100 + 6355441 = 3810^2 + 2521^2 .

It is a cyclic number.

It is not a de Polignac number, because 20871541 - 2⁵ = 20871509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20871551) 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, 2061 + ... + 6781.

It is an arithmetic number, because the mean of its divisors is an integer number (5220171).

Almost surely, 2^20871541 is an apocalyptic number.

It is an amenable number.

20871541 is a deficient number, since it is larger than the sum of its proper divisors (9143).

20871541 is an equidigital number, since it uses as much as digits as its factorization.

20871541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9142.

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 20871541 is about 4568.5381688238. The cubic root of 20871541 is about 275.3287132617.

It can be divided in two parts, 20871 and 541, that added together give a palindrome (21412).

The spelling of 20871541 in words is "twenty million, eight hundred seventy-one thousand, five hundred forty-one".