21220340 has 24 divisors (see below), whose sum is σ = 46908960. Its totient is φ = 8041248.

The previous prime is 21220333. The next prime is 21220349. The reversal of 21220340 is 4302212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220349) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27542 + ... + 28301.

It is an arithmetic number, because the mean of its divisors is an integer number (1954540).

Almost surely, 2^21220340 is an apocalyptic number.

21220340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21220340 is an abundant number, since it is smaller than the sum of its proper divisors (25688620).

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

21220340 is a wasteful number, since it uses less digits than its factorization.

21220340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55871 (or 55869 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 14.

The square root of 21220340 is about 4606.5540266017. The cubic root of 21220340 is about 276.8539851769.

Adding to 21220340 its reverse (4302212), we get a palindrome (25522552).

The spelling of 21220340 in words is "twenty-one million, two hundred twenty thousand, three hundred forty".