21135929 has 4 divisors (see below), whose sum is σ = 21258276. Its totient is φ = 21013584.

The previous prime is 21135911. The next prime is 21135971. The reversal of 21135929 is 92953112.

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

It can be written as a sum of positive squares in 2 ways, for example, as 19598329 + 1537600 = 4427^2 + 1240^2 .

It is a cyclic number.

It is not a de Polignac number, because 21135929 - 2¹⁶ = 21070393 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21135895 and 21135904.

It is not an unprimeable number, because it can be changed into a prime (21135329) 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, 60914 + ... + 61259.

It is an arithmetic number, because the mean of its divisors is an integer number (5314569).

Almost surely, 2^21135929 is an apocalyptic number.

It is an amenable number.

21135929 is a deficient number, since it is larger than the sum of its proper divisors (122347).

21135929 is a wasteful number, since it uses less digits than its factorization.

21135929 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122346.

The product of its digits is 4860, while the sum is 32.

The square root of 21135929 is about 4597.3828424442. The cubic root of 21135929 is about 276.4864042444.

The spelling of 21135929 in words is "twenty-one million, one hundred thirty-five thousand, nine hundred twenty-nine".