21320839 has 16 divisors (see below), whose sum is σ = 24330240. Its totient is φ = 18564480.

The previous prime is 21320837. The next prime is 21320851. The reversal of 21320839 is 93802312.

It is a cyclic number.

It is not a de Polignac number, because 21320839 - 2¹ = 21320837 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 (21320833) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11242 + ... + 13000.

It is an arithmetic number, because the mean of its divisors is an integer number (1520640).

Almost surely, 2^21320839 is an apocalyptic number.

21320839 is a deficient number, since it is larger than the sum of its proper divisors (3009401).

21320839 is a wasteful number, since it uses less digits than its factorization.

21320839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1830.

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 21320839 is about 4617.4494041624. The cubic root of 21320839 is about 277.2903548735.

The spelling of 21320839 in words is "twenty-one million, three hundred twenty thousand, eight hundred thirty-nine".