21516044 has 12 divisors (see below), whose sum is σ = 41076168. Its totient is φ = 9780000.

The previous prime is 21516041. The next prime is 21516071. The reversal of 21516044 is 44061512.

It is not an unprimeable number, because it can be changed into a prime (21516041) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 244457 + ... + 244544.

It is an arithmetic number, because the mean of its divisors is an integer number (3423014).

Almost surely, 2^21516044 is an apocalyptic number.

It is an amenable number.

21516044 is a deficient number, since it is larger than the sum of its proper divisors (19560124).

21516044 is a wasteful number, since it uses less digits than its factorization.

21516044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 489016 (or 489014 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 21516044 is about 4638.5389941230. The cubic root of 21516044 is about 278.1340381526.

Adding to 21516044 its reverse (44061512), we get a palindrome (65577556).

The spelling of 21516044 in words is "twenty-one million, five hundred sixteen thousand, forty-four".