21221416 has 8 divisors (see below), whose sum is σ = 39790170. Its totient is φ = 10610704.

The previous prime is 21221411. The next prime is 21221419. The reversal of 21221416 is 61412212.

It can be written as a sum of positive squares in only one way, i.e., 14092516 + 7128900 = 3754^2 + 2670^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a junction number, because it is equal to n+sod(n) for n = 21221393 and 21221402.

It is not an unprimeable number, because it can be changed into a prime (21221411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1326331 + ... + 1326346.

Almost surely, 2^21221416 is an apocalyptic number.

It is an amenable number.

21221416 is a deficient number, since it is larger than the sum of its proper divisors (18568754).

21221416 is a wasteful number, since it uses less digits than its factorization.

21221416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2652683 (or 2652679 counting only the distinct ones).

The product of its digits is 192, while the sum is 19.

The square root of 21221416 is about 4606.6708152417. The cubic root of 21221416 is about 276.8586644902.

Adding to 21221416 its reverse (61412212), we get a palindrome (82633628).

The spelling of 21221416 in words is "twenty-one million, two hundred twenty-one thousand, four hundred sixteen".