21388367 has 32 divisors (see below), whose sum is σ = 29998080. Its totient is φ = 14699520.

The previous prime is 21388333. The next prime is 21388373. The reversal of 21388367 is 76388312.

It is a happy number.

It is not a de Polignac number, because 21388367 - 2²² = 17194063 is a prime.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 21388367.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21388327) 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 31 ways as a sum of consecutive naturals, for example, 22559 + ... + 23487.

It is an arithmetic number, because the mean of its divisors is an integer number (937440).

Almost surely, 2^21388367 is an apocalyptic number.

21388367 is a deficient number, since it is larger than the sum of its proper divisors (8609713).

21388367 is a wasteful number, since it uses less digits than its factorization.

21388367 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 983.

The product of its digits is 48384, while the sum is 38.

The square root of 21388367 is about 4624.7558854495. The cubic root of 21388367 is about 277.5827937897.

Subtracting 21388367 from its reverse (76388312), we obtain a palindrome (54999945).

The spelling of 21388367 in words is "twenty-one million, three hundred eighty-eight thousand, three hundred sixty-seven".