21081646221 has 8 divisors (see below), whose sum is σ = 28112571840. Its totient is φ = 14052575712.

The previous prime is 21081646219. The next prime is 21081646253. The reversal of 21081646221 is 12264618012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21081646221 - 2¹ = 21081646219 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21081646021) 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, 437040 + ... + 482873.

It is an arithmetic number, because the mean of its divisors is an integer number (3514071480).

Almost surely, 2^21081646221 is an apocalyptic number.

It is an amenable number.

21081646221 is a deficient number, since it is larger than the sum of its proper divisors (7030925619).

21081646221 is an equidigital number, since it uses as much as digits as its factorization.

21081646221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 927555.

The product of its (nonzero) digits is 9216, while the sum is 33.

The spelling of 21081646221 in words is "twenty-one billion, eighty-one million, six hundred forty-six thousand, two hundred twenty-one".