21324340 has 12 divisors (see below), whose sum is σ = 44781156. Its totient is φ = 8529728.

The previous prime is 21324313. The next prime is 21324361. The reversal of 21324340 is 4342312.

It can be written as a sum of positive squares in 2 ways, for example, as 6853924 + 14470416 = 2618^2 + 3804^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 533089 + ... + 533128.

It is an arithmetic number, because the mean of its divisors is an integer number (3731763).

Almost surely, 2^21324340 is an apocalyptic number.

21324340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21324340 is an abundant number, since it is smaller than the sum of its proper divisors (23456816).

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

21324340 is a wasteful number, since it uses less digits than its factorization.

21324340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1066226 (or 1066224 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 19.

The square root of 21324340 is about 4617.8284940002. The cubic root of 21324340 is about 277.3055315809.

Adding to 21324340 its reverse (4342312), we get a palindrome (25666652).

The spelling of 21324340 in words is "twenty-one million, three hundred twenty-four thousand, three hundred forty".