21306841 has 4 divisors (see below), whose sum is σ = 21368592. Its totient is φ = 21245092.

The previous prime is 21306823. The next prime is 21306869. The reversal of 21306841 is 14860312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21306841 - 2⁷ = 21306713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21306811) 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 in 3 ways as a sum of consecutive naturals, for example, 30355 + ... + 31048.

It is an arithmetic number, because the mean of its divisors is an integer number (5342148).

Almost surely, 2^21306841 is an apocalyptic number.

It is an amenable number.

21306841 is a deficient number, since it is larger than the sum of its proper divisors (61751).

21306841 is an equidigital number, since it uses as much as digits as its factorization.

21306841 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61750.

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 21306841 is about 4615.9333834015. The cubic root of 21306841 is about 277.2296574474.

The spelling of 21306841 in words is "twenty-one million, three hundred six thousand, eight hundred forty-one".