21789138 has 32 divisors (see below), whose sum is σ = 52735104. Its totient is φ = 5859072.

The previous prime is 21789127. The next prime is 21789151. The reversal of 21789138 is 83198712.

It is a junction number, because it is equal to n+sod(n) for n = 21789096 and 21789105.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 14545 + ... + 15972.

It is an arithmetic number, because the mean of its divisors is an integer number (1647972).

Almost surely, 2^21789138 is an apocalyptic number.

21789138 is an abundant number, since it is smaller than the sum of its proper divisors (30945966).

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

21789138 is a wasteful number, since it uses less digits than its factorization.

21789138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30546.

The product of its digits is 24192, while the sum is 39.

The square root of 21789138 is about 4667.8836746431. The cubic root of 21789138 is about 279.3058400243.

The spelling of 21789138 in words is "twenty-one million, seven hundred eighty-nine thousand, one hundred thirty-eight".