21533316 has 24 divisors (see below), whose sum is σ = 57422400. Its totient is φ = 6152352.

The previous prime is 21533293. The next prime is 21533333. The reversal of 21533316 is 61333512.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 128091 + ... + 128258.

It is an arithmetic number, because the mean of its divisors is an integer number (2392600).

Almost surely, 2^21533316 is an apocalyptic number.

It is an amenable number.

21533316 is an abundant number, since it is smaller than the sum of its proper divisors (35889084).

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

21533316 is a wasteful number, since it uses less digits than its factorization.

21533316 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 256363 (or 256361 counting only the distinct ones).

The product of its digits is 1620, while the sum is 24.

The square root of 21533316 is about 4640.4004137574. The cubic root of 21533316 is about 278.2084422613.

Adding to 21533316 its reverse (61333512), we get a palindrome (82866828).

The spelling of 21533316 in words is "twenty-one million, five hundred thirty-three thousand, three hundred sixteen".