21393828 has 24 divisors (see below), whose sum is σ = 55465760. Its totient is φ = 7131240.

The previous prime is 21393809. The next prime is 21393847. The reversal of 21393828 is 82839312.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21393809) and next prime (21393847).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21393792 and 21393801.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 98938 + ... + 99153.

Almost surely, 2^21393828 is an apocalyptic number.

It is an amenable number.

21393828 is an abundant number, since it is smaller than the sum of its proper divisors (34071932).

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

21393828 is a wasteful number, since it uses less digits than its factorization.

21393828 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198104 (or 198096 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 21393828 is about 4625.3462573087. The cubic root of 21393828 is about 277.6064164540.

The spelling of 21393828 in words is "twenty-one million, three hundred ninety-three thousand, eight hundred twenty-eight".