21378355 has 8 divisors (see below), whose sum is σ = 26089200. Its totient is φ = 16812576.

The previous prime is 21378349. The next prime is 21378359. The reversal of 21378355 is 55387312.

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 21378355 - 2³ = 21378347 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21378355.

It is not an unprimeable number, because it can be changed into a prime (21378359) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35940 + ... + 36529.

It is an arithmetic number, because the mean of its divisors is an integer number (3261150).

Almost surely, 2^21378355 is an apocalyptic number.

21378355 is a deficient number, since it is larger than the sum of its proper divisors (4710845).

21378355 is an equidigital number, since it uses as much as digits as its factorization.

21378355 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72533.

The product of its digits is 25200, while the sum is 34.

The square root of 21378355 is about 4623.6733232355. The cubic root of 21378355 is about 277.5394744051.

The spelling of 21378355 in words is "twenty-one million, three hundred seventy-eight thousand, three hundred fifty-five".