21836929 has 3 divisors (see below), whose sum is σ = 21841603. Its totient is φ = 21832256.

The previous prime is 21836921. The next prime is 21836939. The reversal of 21836929 is 92963812.

It is a happy number.

The square root of 21836929 is 4673.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 20930625 + 906304 = 4575^2 + 952^2 .

It is not a de Polignac number, because 21836929 - 2³ = 21836921 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors.

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

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21836891 and 21836900.

It is not an unprimeable number, because it can be changed into a prime (21836921) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 2337 + ... + 7009.

Almost surely, 2^21836929 is an apocalyptic number.

21836929 is the 4673-rd square number.

21836929 is the 2337-th centered octagonal number.

It is an amenable number.

21836929 is a deficient number, since it is larger than the sum of its proper divisors (4674).

21836929 is an frugal number, since it uses more digits than its factorization.

21836929 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9346 (or 4673 counting only the distinct ones).

The product of its digits is 46656, while the sum is 40.

The cubic root of 21836929 is about 279.5098951847.

Multiplying 21836929 by its product of digits (46656), we get a square (1018823759424 = 1009368²).

The spelling of 21836929 in words is "twenty-one million, eight hundred thirty-six thousand, nine hundred twenty-nine".