21378803 has 4 divisors (see below), whose sum is σ = 21489768. Its totient is φ = 21267840.

The previous prime is 21378767. The next prime is 21378817. The reversal of 21378803 is 30887312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21378803 - 2⁸ = 21378547 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21378803.

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

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55193 + ... + 55578.

It is an arithmetic number, because the mean of its divisors is an integer number (5372442).

Almost surely, 2^21378803 is an apocalyptic number.

21378803 is a deficient number, since it is larger than the sum of its proper divisors (110965).

21378803 is a wasteful number, since it uses less digits than its factorization.

21378803 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110964.

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

The square root of 21378803 is about 4623.7217693110. The cubic root of 21378803 is about 277.5414130765.

The spelling of 21378803 in words is "twenty-one million, three hundred seventy-eight thousand, eight hundred three".