21553312 has 24 divisors (see below), whose sum is σ = 46291392. Its totient is φ = 9796800.

The previous prime is 21553309. The next prime is 21553319. The reversal of 21553312 is 21335512.

It is a super-3 number, since 3×21553312³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is not an unprimeable number, because it can be changed into a prime (21553319) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30264 + ... + 30967.

It is an arithmetic number, because the mean of its divisors is an integer number (1928808).

Almost surely, 2^21553312 is an apocalyptic number.

21553312 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21553312 is an abundant number, since it is smaller than the sum of its proper divisors (24738080).

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

21553312 is a wasteful number, since it uses less digits than its factorization.

21553312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61252 (or 61244 counting only the distinct ones).

The product of its digits is 900, while the sum is 22.

The square root of 21553312 is about 4642.5544692550. The cubic root of 21553312 is about 278.2945311067.

Adding to 21553312 its reverse (21335512), we get a palindrome (42888824).

The spelling of 21553312 in words is "twenty-one million, five hundred fifty-three thousand, three hundred twelve".