21215044 has 6 divisors (see below), whose sum is σ = 37126334. Its totient is φ = 10607520.

The previous prime is 21215027. The next prime is 21215053. The reversal of 21215044 is 44051212.

It can be written as a sum of positive squares in only one way, i.e., 19360000 + 1855044 = 4400^2 + 1362^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2651877 + ... + 2651884.

Almost surely, 2^21215044 is an apocalyptic number.

It is an amenable number.

21215044 is a deficient number, since it is larger than the sum of its proper divisors (15911290).

21215044 is a wasteful number, since it uses less digits than its factorization.

21215044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5303765 (or 5303763 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 19.

The square root of 21215044 is about 4605.9791575733. The cubic root of 21215044 is about 276.8309516048.

Adding to 21215044 its reverse (44051212), we get a palindrome (65266256).

The spelling of 21215044 in words is "twenty-one million, two hundred fifteen thousand, forty-four".