21355312 has 40 divisors (see below), whose sum is σ = 45836352. Its totient is φ = 9556800.

The previous prime is 21355291. The next prime is 21355351.

21355312 is nontrivially palindromic in base 10.

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

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, 10887 + ... + 12697.

Almost surely, 2^21355312 is an apocalyptic number.

21355312 is a gapful number since it is divisible by the number (22) 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 21355312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22918176).

21355312 is an abundant number, since it is smaller than the sum of its proper divisors (24481040).

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

21355312 is a wasteful number, since it uses less digits than its factorization.

21355312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1897 (or 1891 counting only the distinct ones).

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

The square root of 21355312 is about 4621.1808014835. The cubic root of 21355312 is about 277.4397217774.

It can be divided in two parts, 2135 and 5312, that added together give a palindrome (7447).

The spelling of 21355312 in words is "twenty-one million, three hundred fifty-five thousand, three hundred twelve".