21036765 has 32 divisors (see below), whose sum is σ = 34747776. Its totient is φ = 10863360.

The previous prime is 21036751. The next prime is 21036767. The reversal of 21036765 is 56763012.

It is not a de Polignac number, because 21036765 - 2⁴ = 21036749 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21036767) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 75807 + ... + 76083.

It is an arithmetic number, because the mean of its divisors is an integer number (1085868).

Almost surely, 2^21036765 is an apocalyptic number.

It is an amenable number.

21036765 is a deficient number, since it is larger than the sum of its proper divisors (13711011).

21036765 is a wasteful number, since it uses less digits than its factorization.

21036765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 429.

The product of its (nonzero) digits is 7560, while the sum is 30.

The square root of 21036765 is about 4586.5853311587. The cubic root of 21036765 is about 276.0533267050.

Adding to 21036765 its reverse (56763012), we get a palindrome (77799777).

The spelling of 21036765 in words is "twenty-one million, thirty-six thousand, seven hundred sixty-five".