21553416 has 48 divisors (see below), whose sum is σ = 61811100. Its totient is φ = 6761472.

The previous prime is 21553403. The next prime is 21553417. The reversal of 21553416 is 61435512.

It can be written as a sum of positive squares in 2 ways, for example, as 19980900 + 1572516 = 4470^2 + 1254^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21553416.

It is not an unprimeable number, because it can be changed into a prime (21553417) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7581 + ... + 10028.

Almost surely, 2^21553416 is an apocalyptic number.

It is an amenable number.

21553416 is an abundant number, since it is smaller than the sum of its proper divisors (40257684).

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

21553416 is a wasteful number, since it uses less digits than its factorization.

21553416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17638 (or 17631 counting only the distinct ones).

The product of its digits is 3600, while the sum is 27.

The square root of 21553416 is about 4642.5656699717. The cubic root of 21553416 is about 278.2949787190.

Adding to 21553416 its reverse (61435512), we get a palindrome (82988928).

The spelling of 21553416 in words is "twenty-one million, five hundred fifty-three thousand, four hundred sixteen".