21138084 has 84 divisors (see below), whose sum is σ = 60595920. Its totient is φ = 6395760.

The previous prime is 21138077. The next prime is 21138101. The reversal of 21138084 is 48083112.

It is a super-3 number, since 3×21138084³ (a number of 23 digits) contains 333 as substring.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 31747 + ... + 32405.

It is an arithmetic number, because the mean of its divisors is an integer number (721380).

Almost surely, 2^21138084 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 21138084, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30297960).

21138084 is an abundant number, since it is smaller than the sum of its proper divisors (39457836).

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

21138084 is a wasteful number, since it uses less digits than its factorization.

21138084 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 692 (or 675 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 21138084 is about 4597.6172089464. The cubic root of 21138084 is about 276.4958006920.

The spelling of 21138084 in words is "twenty-one million, one hundred thirty-eight thousand, eighty-four".