21808934 has 24 divisors (see below), whose sum is σ = 38655504. Its totient is φ = 9039600.

The previous prime is 21808933. The next prime is 21808939. The reversal of 21808934 is 43980812.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21808894 and 21808903.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21808933) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12644 + ... + 14264.

It is an arithmetic number, because the mean of its divisors is an integer number (1610646).

Almost surely, 2^21808934 is an apocalyptic number.

21808934 is a deficient number, since it is larger than the sum of its proper divisors (16846570).

21808934 is a wasteful number, since it uses less digits than its factorization.

21808934 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1692 (or 1661 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 35.

The square root of 21808934 is about 4670.0036402555. The cubic root of 21808934 is about 279.3903999672.

The spelling of 21808934 in words is "twenty-one million, eight hundred eight thousand, nine hundred thirty-four".