21340428 has 24 divisors (see below), whose sum is σ = 50426880. Its totient is φ = 7023120.

The previous prime is 21340421. The next prime is 21340441. The reversal of 21340428 is 82404312.

It is a junction number, because it is equal to n+sod(n) for n = 21340398 and 21340407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21340421) 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, 10308 + ... + 12203.

It is an arithmetic number, because the mean of its divisors is an integer number (2101120).

Almost surely, 2^21340428 is an apocalyptic number.

It is an amenable number.

21340428 is an abundant number, since it is smaller than the sum of its proper divisors (29086452).

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

21340428 is a wasteful number, since it uses less digits than its factorization.

21340428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22597 (or 22595 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 24.

The square root of 21340428 is about 4619.5701098695. The cubic root of 21340428 is about 277.3752511272.

The spelling of 21340428 in words is "twenty-one million, three hundred forty thousand, four hundred twenty-eight".