21378804 has 12 divisors (see below), whose sum is σ = 49883904. Its totient is φ = 7126264.

The previous prime is 21378767. The next prime is 21378817. The reversal of 21378804 is 40887312.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-4 number, since 4×21378804⁴ (a number of 30 digits) contains 4444 as substring.

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 3 ways as a sum of consecutive naturals, for example, 890772 + ... + 890795.

It is an arithmetic number, because the mean of its divisors is an integer number (4156992).

Almost surely, 2^21378804 is an apocalyptic number.

It is an amenable number.

21378804 is an abundant number, since it is smaller than the sum of its proper divisors (28505100).

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

21378804 is a wasteful number, since it uses less digits than its factorization.

21378804 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1781574 (or 1781572 counting only the distinct ones).

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

The square root of 21378804 is about 4623.7218774489. The cubic root of 21378804 is about 277.5414174038.

The spelling of 21378804 in words is "twenty-one million, three hundred seventy-eight thousand, eight hundred four".