21182004 has 18 divisors (see below), whose sum is σ = 53543490. Its totient is φ = 7060656.

The previous prime is 21181999. The next prime is 21182009. The reversal of 21182004 is 40028112.

It is an interprime number because it is at equal distance from previous prime (21181999) and next prime (21182009).

It can be written as a sum of positive squares in only one way, i.e., 21178404 + 3600 = 4602^2 + 60^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21182009) 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 5 ways as a sum of consecutive naturals, for example, 294159 + ... + 294230.

Almost surely, 2^21182004 is an apocalyptic number.

It is an amenable number.

21182004 is an abundant number, since it is smaller than the sum of its proper divisors (32361486).

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

21182004 is a wasteful number, since it uses less digits than its factorization.

21182004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 588399 (or 588394 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The square root of 21182004 is about 4602.3911176692. The cubic root of 21182004 is about 276.6871661074.

It can be divided in two parts, 211 and 82004, that added together give a triangular number (82215 = T₄₀₅).

The spelling of 21182004 in words is "twenty-one million, one hundred eighty-two thousand, four".