21343428 has 18 divisors (see below), whose sum is σ = 53951534. Its totient is φ = 7114464.

The previous prime is 21343373. The next prime is 21343429. The reversal of 21343428 is 82434312.

It can be written as a sum of positive squares in only one way, i.e., 15350724 + 5992704 = 3918^2 + 2448^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is not an unprimeable number, because it can be changed into a prime (21343429) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 296401 + ... + 296472.

Almost surely, 2^21343428 is an apocalyptic number.

It is an amenable number.

21343428 is an abundant number, since it is smaller than the sum of its proper divisors (32608106).

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

21343428 is a wasteful number, since it uses less digits than its factorization.

21343428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 592883 (or 592878 counting only the distinct ones).

The product of its digits is 4608, while the sum is 27.

The square root of 21343428 is about 4619.8948039972. The cubic root of 21343428 is about 277.3882481606.

The spelling of 21343428 in words is "twenty-one million, three hundred forty-three thousand, four hundred twenty-eight".