21040044 has 24 divisors (see below), whose sum is σ = 49168560. Its totient is φ = 7002624.

The previous prime is 21040043. The next prime is 21040057. The reversal of 21040044 is 44004012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21040043) 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, 12772 + ... + 14324.

It is an arithmetic number, because the mean of its divisors is an integer number (2048690).

Almost surely, 2^21040044 is an apocalyptic number.

It is an amenable number.

21040044 is an abundant number, since it is smaller than the sum of its proper divisors (28128516).

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

21040044 is a wasteful number, since it uses less digits than its factorization.

21040044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2689 (or 2687 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 15.

The square root of 21040044 is about 4586.9427726973. The cubic root of 21040044 is about 276.0676687681.

Adding to 21040044 its reverse (44004012), we get a palindrome (65044056).

The spelling of 21040044 in words is "twenty-one million, forty thousand, forty-four".