21385115 has 4 divisors (see below), whose sum is σ = 25662144. Its totient is φ = 17108088.

The previous prime is 21385109. The next prime is 21385123. The reversal of 21385115 is 51158312.

It is a happy number.

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 21385115 - 2¹⁸ = 21122971 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2138507 + ... + 2138516.

It is an arithmetic number, because the mean of its divisors is an integer number (6415536).

Almost surely, 2^21385115 is an apocalyptic number.

21385115 is a deficient number, since it is larger than the sum of its proper divisors (4277029).

21385115 is an equidigital number, since it uses as much as digits as its factorization.

21385115 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4277028.

The product of its digits is 1200, while the sum is 26.

The square root of 21385115 is about 4624.4042859594. The cubic root of 21385115 is about 277.5687246932.

The spelling of 21385115 in words is "twenty-one million, three hundred eighty-five thousand, one hundred fifteen".