81224621221 has 8 divisors (see below), whose sum is σ = 83448147744. Its totient is φ = 79002582480.

The previous prime is 81224621173. The next prime is 81224621237. The reversal of 81224621221 is 12212642218.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 81224621221 - 2¹⁵ = 81224588453 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81224621021) 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, 260815 + ... + 480076.

It is an arithmetic number, because the mean of its divisors is an integer number (10431018468).

Almost surely, 2^81224621221 is an apocalyptic number.

It is an amenable number.

81224621221 is a deficient number, since it is larger than the sum of its proper divisors (2223526523).

81224621221 is a wasteful number, since it uses less digits than its factorization.

81224621221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 743891.

The product of its digits is 6144, while the sum is 31.

The spelling of 81224621221 in words is "eighty-one billion, two hundred twenty-four million, six hundred twenty-one thousand, two hundred twenty-one".