21090044 has 12 divisors (see below), whose sum is σ = 38098368. Its totient is φ = 10204800.

The previous prime is 21090007. The next prime is 21090061. The reversal of 21090044 is 44009012.

It is a junction number, because it is equal to n+sod(n) for n = 21089998 and 21090025.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 84917 + ... + 85164.

It is an arithmetic number, because the mean of its divisors is an integer number (3174864).

Almost surely, 2^21090044 is an apocalyptic number.

It is an amenable number.

21090044 is a deficient number, since it is larger than the sum of its proper divisors (17008324).

21090044 is a wasteful number, since it uses less digits than its factorization.

21090044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170116 (or 170114 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 21090044 is about 4592.3897918186. The cubic root of 21090044 is about 276.2861800924.

Adding to 21090044 its reverse (44009012), we get a palindrome (65099056).

The spelling of 21090044 in words is "twenty-one million, ninety thousand, forty-four".