21636735 has 16 divisors (see below), whose sum is σ = 34676736. Its totient is φ = 11520288.

The previous prime is 21636709. The next prime is 21636743. The reversal of 21636735 is 53763612.

It is not a de Polignac number, because 21636735 - 2²⁰ = 20588159 is a prime.

It is a plaindrome in base 11.

It is a junction number, because it is equal to n+sod(n) for n = 21636696 and 21636705.

It is a congruent number.

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, 15642 + ... + 16968.

It is an arithmetic number, because the mean of its divisors is an integer number (2167296).

Almost surely, 2^21636735 is an apocalyptic number.

21636735 is a deficient number, since it is larger than the sum of its proper divisors (13040001).

21636735 is a wasteful number, since it uses less digits than its factorization.

21636735 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2422.

The product of its digits is 22680, while the sum is 33.

The square root of 21636735 is about 4651.5303933222. The cubic root of 21636735 is about 278.6531190871.

It can be divided in two parts, 21 and 636735, that added together give a triangular number (636756 = T₁₁₂₈).

The spelling of 21636735 in words is "twenty-one million, six hundred thirty-six thousand, seven hundred thirty-five".