21388704 has 24 divisors (see below), whose sum is σ = 56145600. Its totient is φ = 7129536.

The previous prime is 21388691. The next prime is 21388709. The reversal of 21388704 is 40788312.

It is a tau number, because it is divible by the number of its divisors (24).

It is not an unprimeable number, because it can be changed into a prime (21388709) 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 3 ways as a sum of consecutive naturals, for example, 111304 + ... + 111495.

It is an arithmetic number, because the mean of its divisors is an integer number (2339400).

Almost surely, 2^21388704 is an apocalyptic number.

21388704 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21388704 is an abundant number, since it is smaller than the sum of its proper divisors (34756896).

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

21388704 is a wasteful number, since it uses less digits than its factorization.

21388704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222812 (or 222804 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 33.

The square root of 21388704 is about 4624.7923196615. The cubic root of 21388704 is about 277.5842516680.

The spelling of 21388704 in words is "twenty-one million, three hundred eighty-eight thousand, seven hundred four".