81438678100221 has 8 divisors (see below), whose sum is σ = 116937589067040. Its totient is φ = 50116109600112.

The previous prime is 81438678100207. The next prime is 81438678100249. The reversal of 81438678100221 is 12200187683418.

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 81438678100221 - 2²⁵ = 81438644545789 is a prime.

It is a super-2 number, since 2×81438678100221² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81438678100121) 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, 1044085616631 + ... + 1044085616708.

It is an arithmetic number, because the mean of its divisors is an integer number (14617198633380).

Almost surely, 2^{81438678100221} is an apocalyptic number.

It is an amenable number.

81438678100221 is a deficient number, since it is larger than the sum of its proper divisors (35498910966819).

81438678100221 is a wasteful number, since it uses less digits than its factorization.

81438678100221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2088171233355.

The product of its (nonzero) digits is 1032192, while the sum is 51.

The spelling of 81438678100221 in words is "eighty-one trillion, four hundred thirty-eight billion, six hundred seventy-eight million, one hundred thousand, two hundred twenty-one".