21378805 has 8 divisors (see below), whose sum is σ = 29319552. Its totient is φ = 14659728.

The previous prime is 21378767. The next prime is 21378817. The reversal of 21378805 is 50887312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21378805 - 2¹¹ = 21376757 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 305377 + ... + 305446.

It is an arithmetic number, because the mean of its divisors is an integer number (3664944).

Almost surely, 2^21378805 is an apocalyptic number.

It is an amenable number.

21378805 is a deficient number, since it is larger than the sum of its proper divisors (7940747).

21378805 is an equidigital number, since it uses as much as digits as its factorization.

21378805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 610835.

The product of its (nonzero) digits is 13440, while the sum is 34.

The square root of 21378805 is about 4623.7219855869. The cubic root of 21378805 is about 277.5414217312.

The spelling of 21378805 in words is "twenty-one million, three hundred seventy-eight thousand, eight hundred five".