21252416 has 14 divisors (see below), whose sum is σ = 42172890. Its totient is φ = 10626176.

The previous prime is 21252403. The next prime is 21252433. The reversal of 21252416 is 61425212.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 21160000 + 92416 = 4600^2 + 304^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21252391 and 21252400.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165971 + ... + 166098.

Almost surely, 2^21252416 is an apocalyptic number.

It is an amenable number.

21252416 is a deficient number, since it is larger than the sum of its proper divisors (20920474).

21252416 is an equidigital number, since it uses as much as digits as its factorization.

21252416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 332081 (or 332071 counting only the distinct ones).

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

The square root of 21252416 is about 4610.0342731915. The cubic root of 21252416 is about 276.9934095492.

Adding to 21252416 its reverse (61425212), we get a palindrome (82677628).

The spelling of 21252416 in words is "twenty-one million, two hundred fifty-two thousand, four hundred sixteen".