21358541 has 4 divisors (see below), whose sum is σ = 21369372. Its totient is φ = 21347712.

The previous prime is 21358537. The next prime is 21358549. The reversal of 21358541 is 14585312.

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 13213225 + 8145316 = 3635^2 + 2854^2 .

It is a cyclic number.

It is not a de Polignac number, because 21358541 - 2² = 21358537 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21358549) 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, 1526 + ... + 6711.

It is an arithmetic number, because the mean of its divisors is an integer number (5342343).

Almost surely, 2^21358541 is an apocalyptic number.

It is an amenable number.

21358541 is a deficient number, since it is larger than the sum of its proper divisors (10831).

21358541 is an equidigital number, since it uses as much as digits as its factorization.

21358541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10830.

The product of its digits is 4800, while the sum is 29.

The square root of 21358541 is about 4621.5301578590. The cubic root of 21358541 is about 277.4537043673.

The spelling of 21358541 in words is "twenty-one million, three hundred fifty-eight thousand, five hundred forty-one".