21198641 has 4 divisors (see below), whose sum is σ = 21558000. Its totient is φ = 20839284.

The previous prime is 21198631. The next prime is 21198673. The reversal of 21198641 is 14689112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21198641 - 2¹⁸ = 20936497 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21198598 and 21198607.

It is not an unprimeable number, because it can be changed into a prime (21198631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 179591 + ... + 179708.

It is an arithmetic number, because the mean of its divisors is an integer number (5389500).

Almost surely, 2^21198641 is an apocalyptic number.

It is an amenable number.

21198641 is a deficient number, since it is larger than the sum of its proper divisors (359359).

21198641 is an equidigital number, since it uses as much as digits as its factorization.

21198641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 359358.

The product of its digits is 3456, while the sum is 32.

The square root of 21198641 is about 4604.1981929539. The cubic root of 21198641 is about 276.7595866982.

The spelling of 21198641 in words is "twenty-one million, one hundred ninety-eight thousand, six hundred forty-one".