21019404 has 48 divisors (see below), whose sum is σ = 57575168. Its totient is φ = 5842368.

The previous prime is 21019393. The next prime is 21019409. The reversal of 21019404 is 40491012.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (21019409) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 274 + ... + 6489.

Almost surely, 2^21019404 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21019404, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28787584).

21019404 is an abundant number, since it is smaller than the sum of its proper divisors (36555764).

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

21019404 is a wasteful number, since it uses less digits than its factorization.

21019404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6814 (or 6812 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 21019404 is about 4584.6923560911. The cubic root of 21019404 is about 275.9773663439.

The spelling of 21019404 in words is "twenty-one million, nineteen thousand, four hundred four".