21545316 has 72 divisors (see below), whose sum is σ = 61763520. Its totient is φ = 6277824.

The previous prime is 21545311. The next prime is 21545327. The reversal of 21545316 is 61354512.

It is a self number, because there is not a number n which added to its sum of digits gives 21545316.

It is not an unprimeable number, because it can be changed into a prime (21545311) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7681 + ... + 10103.

Almost surely, 2^21545316 is an apocalyptic number.

21545316 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21545316, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30881760).

21545316 is an abundant number, since it is smaller than the sum of its proper divisors (40218204).

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

21545316 is a wasteful number, since it uses less digits than its factorization.

21545316 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2465 (or 2460 counting only the distinct ones).

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

The square root of 21545316 is about 4641.6932255374. The cubic root of 21545316 is about 278.2601122927.

Adding to 21545316 its reverse (61354512), we get a palindrome (82899828).

The spelling of 21545316 in words is "twenty-one million, five hundred forty-five thousand, three hundred sixteen".