21036839 has 4 divisors (see below), whose sum is σ = 21049656. Its totient is φ = 21024024.

The previous prime is 21036833. The next prime is 21036877. The reversal of 21036839 is 93863012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21036839 is a prime.

It is a super-2 number, since 2×21036839² = 885097190223842, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21036833) 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, 3509 + ... + 7374.

It is an arithmetic number, because the mean of its divisors is an integer number (5262414).

Almost surely, 2^21036839 is an apocalyptic number.

21036839 is a deficient number, since it is larger than the sum of its proper divisors (12817).

21036839 is a wasteful number, since it uses less digits than its factorization.

21036839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12816.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 21036839 is about 4586.5933981551. The cubic root of 21036839 is about 276.0536503910.

The spelling of 21036839 in words is "twenty-one million, thirty-six thousand, eight hundred thirty-nine".