21098365 has 4 divisors (see below), whose sum is σ = 25318044. Its totient is φ = 16878688.

The previous prime is 21098359. The next prime is 21098369. The reversal of 21098365 is 56389012.

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 3617604 + 17480761 = 1902^2 + 4181^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21098365 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21098365.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21098369) 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, 2109832 + ... + 2109841.

It is an arithmetic number, because the mean of its divisors is an integer number (6329511).

Almost surely, 2^21098365 is an apocalyptic number.

It is an amenable number.

21098365 is a deficient number, since it is larger than the sum of its proper divisors (4219679).

21098365 is an equidigital number, since it uses as much as digits as its factorization.

21098365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4219678.

The product of its (nonzero) digits is 12960, while the sum is 34.

The square root of 21098365 is about 4593.2956578039. The cubic root of 21098365 is about 276.3225112165.

The spelling of 21098365 in words is "twenty-one million, ninety-eight thousand, three hundred sixty-five".