21184540 has 48 divisors (see below), whose sum is σ = 48756960. Its totient is φ = 7683840.

The previous prime is 21184523. The next prime is 21184547. The reversal of 21184540 is 4548112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21184547) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14650 + ... + 16030.

It is an arithmetic number, because the mean of its divisors is an integer number (1015770).

Almost surely, 2^21184540 is an apocalyptic number.

21184540 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 21184540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24378480).

21184540 is an abundant number, since it is smaller than the sum of its proper divisors (27572420).

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

21184540 is a wasteful number, since it uses less digits than its factorization.

21184540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1462 (or 1460 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 25.

The square root of 21184540 is about 4602.6666183855. Note that the first 4 decimals coincide. The cubic root of 21184540 is about 276.6982077232.

The spelling of 21184540 in words is "twenty-one million, one hundred eighty-four thousand, five hundred forty".