21338155 has 4 divisors (see below), whose sum is σ = 25605792. Its totient is φ = 17070520.

The previous prime is 21338153. The next prime is 21338183. The reversal of 21338155 is 55183312.

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

It is not a de Polignac number, because 21338155 - 2¹ = 21338153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21338153) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2133811 + ... + 2133820.

It is an arithmetic number, because the mean of its divisors is an integer number (6401448).

Almost surely, 2^21338155 is an apocalyptic number.

21338155 is a deficient number, since it is larger than the sum of its proper divisors (4267637).

21338155 is an equidigital number, since it uses as much as digits as its factorization.

21338155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4267636.

The product of its digits is 3600, while the sum is 28.

The square root of 21338155 is about 4619.3240847553. The cubic root of 21338155 is about 277.3654028972.

The spelling of 21338155 in words is "twenty-one million, three hundred thirty-eight thousand, one hundred fifty-five".