21808038 has 24 divisors (see below), whose sum is σ = 50737752. Its totient is φ = 6230784.

The previous prime is 21808037. The next prime is 21808051. The reversal of 21808038 is 83080812.

It is a plaindrome in base 11.

It is a junction number, because it is equal to n+sod(n) for n = 21807996 and 21808014.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21808037) 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, 36795 + ... + 37382.

It is an arithmetic number, because the mean of its divisors is an integer number (2114073).

Almost surely, 2^21808038 is an apocalyptic number.

21808038 is an abundant number, since it is smaller than the sum of its proper divisors (28929714).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21808038 is a wasteful number, since it uses less digits than its factorization.

21808038 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74196 (or 74189 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 30.

The square root of 21808038 is about 4669.9077078675. The cubic root of 21808038 is about 279.3865737489.

The spelling of 21808038 in words is "twenty-one million, eight hundred eight thousand, thirty-eight".