21679533 has 6 divisors (see below), whose sum is σ = 31314894. Its totient is φ = 14453016.

The previous prime is 21679477. The next prime is 21679561. The reversal of 21679533 is 33597612.

It can be written as a sum of positive squares in only one way, i.e., 16670889 + 5008644 = 4083^2 + 2238^2 .

It is not a de Polignac number, because 21679533 - 2¹⁰ = 21678509 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21679033) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1204410 + ... + 1204427.

It is an arithmetic number, because the mean of its divisors is an integer number (5219149).

Almost surely, 2^21679533 is an apocalyptic number.

It is an amenable number.

21679533 is a deficient number, since it is larger than the sum of its proper divisors (9635361).

21679533 is a wasteful number, since it uses less digits than its factorization.

21679533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2408843 (or 2408840 counting only the distinct ones).

The product of its digits is 34020, while the sum is 36.

The square root of 21679533 is about 4656.1285420400. The cubic root of 21679533 is about 278.8367256809.

The spelling of 21679533 in words is "twenty-one million, six hundred seventy-nine thousand, five hundred thirty-three".