81921987063399 has 8 divisors (see below), whose sum is σ = 124833504096640. Its totient is φ = 46812564036216.

The previous prime is 81921987063383. The next prime is 81921987063439. The reversal of 81921987063399 is 99336078912918.

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

It is not a de Polignac number, because 81921987063399 - 2⁴ = 81921987063383 is a prime.

It is a super-2 number, since 2×81921987063399² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81921987063399.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81921987063359) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1950523501489 + ... + 1950523501530.

It is an arithmetic number, because the mean of its divisors is an integer number (15604188012080).

Almost surely, 2^{81921987063399} is an apocalyptic number.

81921987063399 is a deficient number, since it is larger than the sum of its proper divisors (42911517033241).

81921987063399 is a wasteful number, since it uses less digits than its factorization.

81921987063399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3901047003029.

The product of its (nonzero) digits is 317447424, while the sum is 75.

The spelling of 81921987063399 in words is "eighty-one trillion, nine hundred twenty-one billion, nine hundred eighty-seven million, sixty-three thousand, three hundred ninety-nine".