21553152 has 56 divisors (see below), whose sum is σ = 57537096. Its totient is φ = 7176192.

The previous prime is 21553141. The next prime is 21553157. The reversal of 21553152 is 25135512.

It is a happy number.

It is a super-2 number, since 2×21553152² = 929076722270208, which contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21553157) 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, 24138 + ... + 25014.

Almost surely, 2^21553152 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21553152, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28768548).

21553152 is an abundant number, since it is smaller than the sum of its proper divisors (35983944).

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

21553152 is an frugal number, since it uses more digits than its factorization.

21553152 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 906 (or 882 counting only the distinct ones).

The product of its digits is 1500, while the sum is 24.

The square root of 21553152 is about 4642.5372373305. The cubic root of 21553152 is about 278.2938424695.

Adding to 21553152 its reverse (25135512), we get a palindrome (46688664).

The spelling of 21553152 in words is "twenty-one million, five hundred fifty-three thousand, one hundred fifty-two".