21384510 has 64 divisors (see below), whose sum is σ = 59443200. Its totient is φ = 4822272.

The previous prime is 21384509. The next prime is 21384511. The reversal of 21384510 is 1548312.

It is an interprime number because it is at equal distance from previous prime (21384509) and next prime (21384511).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21384511) 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 31 ways as a sum of consecutive naturals, for example, 15946 + ... + 17234.

It is an arithmetic number, because the mean of its divisors is an integer number (928800).

Almost surely, 2^21384510 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21384510, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29721600).

21384510 is an abundant number, since it is smaller than the sum of its proper divisors (38058690).

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

21384510 is a wasteful number, since it uses less digits than its factorization.

21384510 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1385.

The product of its (nonzero) digits is 960, while the sum is 24.

The square root of 21384510 is about 4624.3388716659. The cubic root of 21384510 is about 277.5661071301.

The spelling of 21384510 in words is "twenty-one million, three hundred eighty-four thousand, five hundred ten".