21136305 has 16 divisors (see below), whose sum is σ = 33908544. Its totient is φ = 11242560.

The previous prime is 21136277. The next prime is 21136319. The reversal of 21136305 is 50363112.

It is not a de Polignac number, because 21136305 - 2¹⁴ = 21119921 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4642 + ... + 7988.

It is an arithmetic number, because the mean of its divisors is an integer number (2119284).

Almost surely, 2^21136305 is an apocalyptic number.

It is an amenable number.

21136305 is a deficient number, since it is larger than the sum of its proper divisors (12772239).

21136305 is a wasteful number, since it uses less digits than its factorization.

21136305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3776.

The product of its (nonzero) digits is 540, while the sum is 21.

The square root of 21136305 is about 4597.4237350934. The cubic root of 21136305 is about 276.4880437634.

Adding to 21136305 its reverse (50363112), we get a palindrome (71499417).

The spelling of 21136305 in words is "twenty-one million, one hundred thirty-six thousand, three hundred five".