21144884 has 6 divisors (see below), whose sum is σ = 37003554. Its totient is φ = 10572440.

The previous prime is 21144869. The next prime is 21144901. The reversal of 21144884 is 48844112.

It can be written as a sum of positive squares in only one way, i.e., 14227984 + 6916900 = 3772^2 + 2630^2 .

It is a super-2 number, since 2×21144884² = 894212238746912, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21144884.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2643107 + ... + 2643114.

It is an arithmetic number, because the mean of its divisors is an integer number (6167259).

Almost surely, 2^21144884 is an apocalyptic number.

It is an amenable number.

21144884 is a deficient number, since it is larger than the sum of its proper divisors (15858670).

21144884 is a wasteful number, since it uses less digits than its factorization.

21144884 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5286225 (or 5286223 counting only the distinct ones).

The product of its digits is 8192, while the sum is 32.

The square root of 21144884 is about 4598.3566629830. The cubic root of 21144884 is about 276.5254465494.

Adding to 21144884 its reverse (48844112), we get a palindrome (69988996).

The spelling of 21144884 in words is "twenty-one million, one hundred forty-four thousand, eight hundred eighty-four".