21215116641 has 4 divisors (see below), whose sum is σ = 28286822192. Its totient is φ = 14143411092.

The previous prime is 21215116597. The next prime is 21215116649. The reversal of 21215116641 is 14661151212.

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 not a de Polignac number, because 21215116641 - 2¹⁰ = 21215115617 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21215116599 and 21215116608.

It is not an unprimeable number, because it can be changed into a prime (21215116649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3535852771 + ... + 3535852776.

It is an arithmetic number, because the mean of its divisors is an integer number (7071705548).

Almost surely, 2^21215116641 is an apocalyptic number.

It is an amenable number.

21215116641 is a deficient number, since it is larger than the sum of its proper divisors (7071705551).

21215116641 is an equidigital number, since it uses as much as digits as its factorization.

21215116641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7071705550.

The product of its digits is 2880, while the sum is 30.

Adding to 21215116641 its reverse (14661151212), we get a palindrome (35876267853).

The spelling of 21215116641 in words is "twenty-one billion, two hundred fifteen million, one hundred sixteen thousand, six hundred forty-one".