21172416 has 28 divisors (see below), whose sum is σ = 56019192. Its totient is φ = 7057408.

The previous prime is 21172381. The next prime is 21172423. The reversal of 21172416 is 61427112.

It is a Harshad number since it is a multiple of its sum of digits (24).

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 in 3 ways as a sum of consecutive naturals, for example, 54945 + ... + 55328.

Almost surely, 2^21172416 is an apocalyptic number.

It is an amenable number.

21172416 is an abundant number, since it is smaller than the sum of its proper divisors (34846776).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21172416 is a wasteful number, since it uses less digits than its factorization.

21172416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110288 (or 110278 counting only the distinct ones).

The product of its digits is 672, while the sum is 24.

The square root of 21172416 is about 4601.3493673052. The cubic root of 21172416 is about 276.6454124735.

Adding to 21172416 its reverse (61427112), we get a palindrome (82599528).

It can be divided in two parts, 211 and 72416, that added together give a palindrome (72627).

The spelling of 21172416 in words is "twenty-one million, one hundred seventy-two thousand, four hundred sixteen".