21421340 has 12 divisors (see below), whose sum is σ = 44984856. Its totient is φ = 8568528.

The previous prime is 21421333. The next prime is 21421373. The reversal of 21421340 is 4312412.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 535514 + ... + 535553.

It is an arithmetic number, because the mean of its divisors is an integer number (3748738).

Almost surely, 2^21421340 is an apocalyptic number.

21421340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21421340 is an abundant number, since it is smaller than the sum of its proper divisors (23563516).

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

21421340 is a wasteful number, since it uses less digits than its factorization.

21421340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1071076 (or 1071074 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 21421340 is about 4628.3193493967. The cubic root of 21421340 is about 277.7253640959.

Adding to 21421340 its reverse (4312412), we get a palindrome (25733752).

The spelling of 21421340 in words is "twenty-one million, four hundred twenty-one thousand, three hundred forty".