21378843 has 32 divisors (see below), whose sum is σ = 34283520. Its totient is φ = 13115520.

The previous prime is 21378817. The next prime is 21378883. The reversal of 21378843 is 34887312.

It is not a de Polignac number, because 21378843 - 2⁸ = 21378587 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21378798 and 21378807.

It is not an unprimeable number, because it can be changed into a prime (21378883) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 21078 + ... + 22068.

It is an arithmetic number, because the mean of its divisors is an integer number (1071360).

Almost surely, 2^21378843 is an apocalyptic number.

21378843 is a deficient number, since it is larger than the sum of its proper divisors (12904677).

21378843 is a wasteful number, since it uses less digits than its factorization.

21378843 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1064 (or 1058 counting only the distinct ones).

The product of its digits is 32256, while the sum is 36.

The square root of 21378843 is about 4623.7260948287. The cubic root of 21378843 is about 277.5415861708.

The spelling of 21378843 in words is "twenty-one million, three hundred seventy-eight thousand, eight hundred forty-three".