21387384 has 48 divisors (see below), whose sum is σ = 59927400. Its totient is φ = 6882624.

The previous prime is 21387361. The next prime is 21387389. The reversal of 21387384 is 48378312.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21387389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3034 + ... + 7209.

Almost surely, 2^21387384 is an apocalyptic number.

21387384 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21387384 is an abundant number, since it is smaller than the sum of its proper divisors (38540016).

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

21387384 is a wasteful number, since it uses less digits than its factorization.

21387384 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10284 (or 10277 counting only the distinct ones).

The product of its digits is 32256, while the sum is 36.

The square root of 21387384 is about 4624.6496083487. The cubic root of 21387384 is about 277.5785411966.

The spelling of 21387384 in words is "twenty-one million, three hundred eighty-seven thousand, three hundred eighty-four".