21378339 has 24 divisors (see below), whose sum is σ = 32497920. Its totient is φ = 13516272.

The previous prime is 21378319. The next prime is 21378347. The reversal of 21378339 is 93387312.

It is a happy number.

It is not a de Polignac number, because 21378339 - 2⁸ = 21378083 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21378319) 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 23 ways as a sum of consecutive naturals, for example, 28402 + ... + 29144.

It is an arithmetic number, because the mean of its divisors is an integer number (1354080).

Almost surely, 2^21378339 is an apocalyptic number.

21378339 is a deficient number, since it is larger than the sum of its proper divisors (11119581).

21378339 is a wasteful number, since it uses less digits than its factorization.

21378339 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 911 (or 908 counting only the distinct ones).

The product of its digits is 27216, while the sum is 36.

The square root of 21378339 is about 4623.6715930092. The cubic root of 21378339 is about 277.5394051663.

The spelling of 21378339 in words is "twenty-one million, three hundred seventy-eight thousand, three hundred thirty-nine".