21438365 has 16 divisors (see below), whose sum is σ = 29164800. Its totient is φ = 14997312.

The previous prime is 21438359. The next prime is 21438401. The reversal of 21438365 is 56383412.

It is a cyclic number.

It is not a de Polignac number, because 21438365 - 2⁴ = 21438349 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7445 + ... + 9914.

It is an arithmetic number, because the mean of its divisors is an integer number (1822800).

Almost surely, 2^21438365 is an apocalyptic number.

It is an amenable number.

21438365 is a deficient number, since it is larger than the sum of its proper divisors (7726435).

21438365 is a wasteful number, since it uses less digits than its factorization.

21438365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17396.

The product of its digits is 17280, while the sum is 32.

The square root of 21438365 is about 4630.1582046405. The cubic root of 21438365 is about 277.7989203759.

The spelling of 21438365 in words is "twenty-one million, four hundred thirty-eight thousand, three hundred sixty-five".