21798169 has 4 divisors (see below), whose sum is σ = 22549860. Its totient is φ = 21046480.

The previous prime is 21798163. The next prime is 21798197. The reversal of 21798169 is 96189712.

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

It can be written as a sum of positive squares in 2 ways, for example, as 14722569 + 7075600 = 3837^2 + 2660^2 .

It is a cyclic number.

It is not a de Polignac number, because 21798169 - 2⁵ = 21798137 is a prime.

It is a super-2 number, since 2×21798169² = 950320343505122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21798163) 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, 375802 + ... + 375859.

It is an arithmetic number, because the mean of its divisors is an integer number (5637465).

Almost surely, 2^21798169 is an apocalyptic number.

21798169 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21798169 is a deficient number, since it is larger than the sum of its proper divisors (751691).

21798169 is an equidigital number, since it uses as much as digits as its factorization.

21798169 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 751690.

The product of its digits is 54432, while the sum is 43.

The square root of 21798169 is about 4668.8509292973. The cubic root of 21798169 is about 279.3444228972.

The spelling of 21798169 in words is "twenty-one million, seven hundred ninety-eight thousand, one hundred sixty-nine".