21039804 has 24 divisors (see below), whose sum is σ = 54547920. Its totient is φ = 7013232.

The previous prime is 21039803. The next prime is 21039817. The reversal of 21039804 is 40893012.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21039803) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 97299 + ... + 97514.

It is an arithmetic number, because the mean of its divisors is an integer number (2272830).

Almost surely, 2^21039804 is an apocalyptic number.

It is an amenable number.

21039804 is an abundant number, since it is smaller than the sum of its proper divisors (33508116).

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

21039804 is a wasteful number, since it uses less digits than its factorization.

21039804 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 194826 (or 194818 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21039804 is about 4586.9166114068. The cubic root of 21039804 is about 276.0666190793.

The spelling of 21039804 in words is "twenty-one million, thirty-nine thousand, eight hundred four".