21320239 has 2 divisors, whose sum is σ = 21320240. Its totient is φ = 21320238.

The previous prime is 21320213. The next prime is 21320267. The reversal of 21320239 is 93202312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21320239 - 2¹¹ = 21318191 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21320209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660119 + 10660120.

It is an arithmetic number, because the mean of its divisors is an integer number (10660120).

Almost surely, 2^21320239 is an apocalyptic number.

21320239 is a deficient number, since it is larger than the sum of its proper divisors (1).

21320239 is an equidigital number, since it uses as much as digits as its factorization.

21320239 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 22.

The square root of 21320239 is about 4617.3844327714. The cubic root of 21320239 is about 277.2877537287.

The spelling of 21320239 in words is "twenty-one million, three hundred twenty thousand, two hundred thirty-nine".