21320841 has 4 divisors (see below), whose sum is σ = 28427792. Its totient is φ = 14213892.

The previous prime is 21320837. The next prime is 21320851. The reversal of 21320841 is 14802312.

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 not a de Polignac number, because 21320841 - 2² = 21320837 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21320801) 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, 3553471 + ... + 3553476.

It is an arithmetic number, because the mean of its divisors is an integer number (7106948).

Almost surely, 2^21320841 is an apocalyptic number.

It is an amenable number.

21320841 is a deficient number, since it is larger than the sum of its proper divisors (7106951).

21320841 is an equidigital number, since it uses as much as digits as its factorization.

21320841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7106950.

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 21320841 is about 4617.4496207322. The cubic root of 21320841 is about 277.2903635439.

The spelling of 21320841 in words is "twenty-one million, three hundred twenty thousand, eight hundred forty-one".