21332340 has 72 divisors (see below), whose sum is σ = 66812928. Its totient is φ = 5503680.

The previous prime is 21332329. The next prime is 21332347. The reversal of 21332340 is 4323312.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21332347) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3669 + ... + 7491.

Almost surely, 2^21332340 is an apocalyptic number.

21332340 is a gapful number since it is divisible by the number (20) 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 21332340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33406464).

21332340 is an abundant number, since it is smaller than the sum of its proper divisors (45480588).

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

21332340 is a wasteful number, since it uses less digits than its factorization.

21332340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3869 (or 3864 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 18.

The square root of 21332340 is about 4618.6946207776. The cubic root of 21332340 is about 277.3402050555.

Adding to 21332340 its reverse (4323312), we get a palindrome (25655652).

Subtracting from 21332340 its reverse (4323312), we obtain a triangular number (17009028 = T₅₈₃₂).

It can be divided in two parts, 2133 and 2340, that multiplied together give a triangular number (4991220 = T₃₁₅₉).

The spelling of 21332340 in words is "twenty-one million, three hundred thirty-two thousand, three hundred forty".