21340140 has 24 divisors (see below), whose sum is σ = 59752560. Its totient is φ = 5690688.

The previous prime is 21340093. The next prime is 21340141. The reversal of 21340140 is 4104312.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21340141) 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, 177775 + ... + 177894.

It is an arithmetic number, because the mean of its divisors is an integer number (2489690).

Almost surely, 2^21340140 is an apocalyptic number.

21340140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21340140 is an abundant number, since it is smaller than the sum of its proper divisors (38412420).

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

21340140 is a wasteful number, since it uses less digits than its factorization.

21340140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 355681 (or 355679 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 21340140 is about 4619.5389380327. The cubic root of 21340140 is about 277.3740033479.

Adding to 21340140 its reverse (4104312), we get a palindrome (25444452).

The spelling of 21340140 in words is "twenty-one million, three hundred forty thousand, one hundred forty".