21397359 has 16 divisors (see below), whose sum is σ = 29988992. Its totient is φ = 13553568.

The previous prime is 21397349. The next prime is 21397379. The reversal of 21397359 is 95379312.

It is not a de Polignac number, because 21397359 - 2¹² = 21393263 is a prime.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21397349) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2532 + ... + 7014.

It is an arithmetic number, because the mean of its divisors is an integer number (1874312).

Almost surely, 2^21397359 is an apocalyptic number.

21397359 is a deficient number, since it is larger than the sum of its proper divisors (8591633).

21397359 is a wasteful number, since it uses less digits than its factorization.

21397359 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4566.

The product of its digits is 51030, while the sum is 39.

The square root of 21397359 is about 4625.7279427134. The cubic root of 21397359 is about 277.6216883716.

The spelling of 21397359 in words is "twenty-one million, three hundred ninety-seven thousand, three hundred fifty-nine".