21135139 has 4 divisors (see below), whose sum is σ = 21149856. Its totient is φ = 21120424.

The previous prime is 21135119. The next prime is 21135143. The reversal of 21135139 is 93153112.

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 21135139 - 2²¹ = 19037987 is a prime.

It is a Duffinian number.

It is a plaindrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (21135109) 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 3 ways as a sum of consecutive naturals, for example, 4939 + ... + 8164.

It is an arithmetic number, because the mean of its divisors is an integer number (5287464).

Almost surely, 2^21135139 is an apocalyptic number.

21135139 is a deficient number, since it is larger than the sum of its proper divisors (14717).

21135139 is a wasteful number, since it uses less digits than its factorization.

21135139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14716.

The product of its digits is 810, while the sum is 25.

The square root of 21135139 is about 4597.2969231930. The cubic root of 21135139 is about 276.4829594470.

The spelling of 21135139 in words is "twenty-one million, one hundred thirty-five thousand, one hundred thirty-nine".