21238387 has 4 divisors (see below), whose sum is σ = 21288096. Its totient is φ = 21188680.

The previous prime is 21238363. The next prime is 21238429. The reversal of 21238387 is 78383212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21238387 - 2¹⁵ = 21205619 is a prime.

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

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21238307) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24208 + ... + 25069.

It is an arithmetic number, because the mean of its divisors is an integer number (5322024).

Almost surely, 2^21238387 is an apocalyptic number.

21238387 is a deficient number, since it is larger than the sum of its proper divisors (49709).

21238387 is an equidigital number, since it uses as much as digits as its factorization.

21238387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49708.

The product of its digits is 16128, while the sum is 34.

The square root of 21238387 is about 4608.5124498042. The cubic root of 21238387 is about 276.9324471327.

The spelling of 21238387 in words is "twenty-one million, two hundred thirty-eight thousand, three hundred eighty-seven".