21798355 has 4 divisors (see below), whose sum is σ = 26158032. Its totient is φ = 17438680.

The previous prime is 21798341. The next prime is 21798367. The reversal of 21798355 is 55389712.

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

It is not a de Polignac number, because 21798355 - 2⁵ = 21798323 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2179831 + ... + 2179840.

It is an arithmetic number, because the mean of its divisors is an integer number (6539508).

Almost surely, 2^21798355 is an apocalyptic number.

21798355 is a deficient number, since it is larger than the sum of its proper divisors (4359677).

21798355 is an equidigital number, since it uses as much as digits as its factorization.

21798355 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4359676.

The product of its digits is 75600, while the sum is 40.

The square root of 21798355 is about 4668.8708485029. The cubic root of 21798355 is about 279.3452174275.

The spelling of 21798355 in words is "twenty-one million, seven hundred ninety-eight thousand, three hundred fifty-five".