21378416 has 10 divisors (see below), whose sum is σ = 41420712. Its totient is φ = 10689200.

The previous prime is 21378407. The next prime is 21378419. The reversal of 21378416 is 61487312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21378419) 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 as a sum of consecutive naturals, namely, 668060 + ... + 668091.

Almost surely, 2^21378416 is an apocalyptic number.

It is an amenable number.

21378416 is a deficient number, since it is larger than the sum of its proper divisors (20042296).

21378416 is a wasteful number, since it uses less digits than its factorization.

21378416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1336159 (or 1336153 counting only the distinct ones).

The product of its digits is 8064, while the sum is 32.

The square root of 21378416 is about 4623.6799197176. The cubic root of 21378416 is about 277.5397383775.

The spelling of 21378416 in words is "twenty-one million, three hundred seventy-eight thousand, four hundred sixteen".