21998245 has 8 divisors (see below), whose sum is σ = 26424216. Its totient is φ = 17581056.

The previous prime is 21998243. The next prime is 21998267. The reversal of 21998245 is 54289912.

It can be written as a sum of positive squares in 4 ways, for example, as 30276 + 21967969 = 174^2 + 4687^2 .

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 21998245 - 2¹ = 21998243 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21998198 and 21998207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21998243) 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, 6349 + ... + 9181.

It is an arithmetic number, because the mean of its divisors is an integer number (3303027).

Almost surely, 2^21998245 is an apocalyptic number.

It is an amenable number.

21998245 is a deficient number, since it is larger than the sum of its proper divisors (4425971).

21998245 is a wasteful number, since it uses less digits than its factorization.

21998245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4391.

The product of its digits is 51840, while the sum is 40.

The square root of 21998245 is about 4690.2286724636. The cubic root of 21998245 is about 280.1964819901.

The spelling of 21998245 in words is "twenty-one million, nine hundred ninety-eight thousand, two hundred forty-five".