21338940 has 144 divisors (see below), whose sum is σ = 72801792. Its totient is φ = 4566144.

The previous prime is 21338929. The next prime is 21338951. The reversal of 21338940 is 4983312.

21338940 = T₉₁ + T₉₂ + ... + T₅₀₄.

It is an interprime number because it is at equal distance from previous prime (21338929) and next prime (21338951).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21338898 and 21338907.

It is a congruent number.

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 47 ways as a sum of consecutive naturals, for example, 453997 + ... + 454043.

It is an arithmetic number, because the mean of its divisors is an integer number (505568).

Almost surely, 2^21338940 is an apocalyptic number.

21338940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21338940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36400896).

21338940 is an abundant number, since it is smaller than the sum of its proper divisors (51462852).

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

21338940 is a wasteful number, since it uses less digits than its factorization.

21338940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136 (or 87 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 30.

The square root of 21338940 is about 4619.4090531149. The cubic root of 21338940 is about 277.3688041467.

The spelling of 21338940 in words is "twenty-one million, three hundred thirty-eight thousand, nine hundred forty".