21641543 has 16 divisors (see below), whose sum is σ = 27495936. Its totient is φ = 16542240.

The previous prime is 21641537. The next prime is 21641579. The reversal of 21641543 is 34514612.

It is not a de Polignac number, because 21641543 - 2¹⁸ = 21379399 is a prime.

It is a super-3 number, since 3×21641543³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21641143) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1430 + ... + 6732.

It is an arithmetic number, because the mean of its divisors is an integer number (1718496).

Almost surely, 2^21641543 is an apocalyptic number.

21641543 is a deficient number, since it is larger than the sum of its proper divisors (5854393).

21641543 is a wasteful number, since it uses less digits than its factorization.

21641543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5374.

The product of its digits is 2880, while the sum is 26.

The square root of 21641543 is about 4652.0471837676. The cubic root of 21641543 is about 278.6737578290.

The spelling of 21641543 in words is "twenty-one million, six hundred forty-one thousand, five hundred forty-three".