21013444 has 24 divisors (see below), whose sum is σ = 38924928. Its totient is φ = 9905280.

The previous prime is 21013427. The next prime is 21013451. The reversal of 21013444 is 44431012.

It is a super-2 number, since 2×21013444² = 883129657482272, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4924 + ... + 8140.

It is an arithmetic number, because the mean of its divisors is an integer number (1621872).

Almost surely, 2^21013444 is an apocalyptic number.

It is an amenable number.

21013444 is a deficient number, since it is larger than the sum of its proper divisors (17911484).

21013444 is a wasteful number, since it uses less digits than its factorization.

21013444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3315 (or 3313 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 21013444 is about 4584.0423209216. The cubic root of 21013444 is about 275.9512796450.

Adding to 21013444 its reverse (44431012), we get a palindrome (65444456).

The spelling of 21013444 in words is "twenty-one million, thirteen thousand, four hundred forty-four".