221181681621 has 16 divisors (see below), whose sum is σ = 296616797568. Its totient is φ = 146600942400.

The previous prime is 221181681613. The next prime is 221181681629. The reversal of 221181681621 is 126186181122.

It is an interprime number because it is at equal distance from previous prime (221181681613) and next prime (221181681629).

It is not a de Polignac number, because 221181681621 - 2³ = 221181681613 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221181681621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221181681629) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2074936 + ... + 2178926.

It is an arithmetic number, because the mean of its divisors is an integer number (18538549848).

Almost surely, 2^221181681621 is an apocalyptic number.

It is an amenable number.

221181681621 is a deficient number, since it is larger than the sum of its proper divisors (75435115947).

221181681621 is a wasteful number, since it uses less digits than its factorization.

221181681621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108092.

The product of its digits is 18432, while the sum is 39.

The spelling of 221181681621 in words is "two hundred twenty-one billion, one hundred eighty-one million, six hundred eighty-one thousand, six hundred twenty-one".