21838516 has 36 divisors (see below), whose sum is σ = 45147648. Its totient is φ = 9214128.

The previous prime is 21838513. The next prime is 21838517. The reversal of 21838516 is 61583812.

It is a plaindrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21838511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12301 + ... + 13963.

Almost surely, 2^21838516 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21838516, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22573824).

21838516 is an abundant number, since it is smaller than the sum of its proper divisors (23309132).

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

21838516 is a wasteful number, since it uses less digits than its factorization.

21838516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1748 (or 1739 counting only the distinct ones).

The product of its digits is 11520, while the sum is 34.

The square root of 21838516 is about 4673.1698021792. The cubic root of 21838516 is about 279.5166661529.

The spelling of 21838516 in words is "twenty-one million, eight hundred thirty-eight thousand, five hundred sixteen".