21105340 has 12 divisors (see below), whose sum is σ = 44321256. Its totient is φ = 8442128.

The previous prime is 21105307. The next prime is 21105341. The reversal of 21105340 is 4350112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21105341) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 527614 + ... + 527653.

It is an arithmetic number, because the mean of its divisors is an integer number (3693438).

Almost surely, 2^21105340 is an apocalyptic number.

21105340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21105340 is an abundant number, since it is smaller than the sum of its proper divisors (23215916).

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

21105340 is a wasteful number, since it uses less digits than its factorization.

21105340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1055276 (or 1055274 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21105340 is about 4594.0548538301. The cubic root of 21105340 is about 276.3529580808.

Adding to 21105340 its reverse (4350112), we get a palindrome (25455452).

The spelling of 21105340 in words is "twenty-one million, one hundred five thousand, three hundred forty".