21311552 has 14 divisors (see below), whose sum is σ = 42290238. Its totient is φ = 10655744.

The previous prime is 21311527. The next prime is 21311599. The reversal of 21311552 is 25511312.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 21307456 + 4096 = 4616^2 + 64^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166433 + ... + 166560.

Almost surely, 2^21311552 is an apocalyptic number.

It is an amenable number.

21311552 is a deficient number, since it is larger than the sum of its proper divisors (20978686).

21311552 is an equidigital number, since it uses as much as digits as its factorization.

21311552 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333005 (or 332995 counting only the distinct ones).

The product of its digits is 300, while the sum is 20.

The square root of 21311552 is about 4616.4436528566. The cubic root of 21311552 is about 277.2500880166.

Adding to 21311552 its reverse (25511312), we get a palindrome (46822864).

The spelling of 21311552 in words is "twenty-one million, three hundred eleven thousand, five hundred fifty-two".