81869121 has 24 divisors (see below), whose sum is σ = 123826560. Its totient is φ = 52024896.

The previous prime is 81869057. The next prime is 81869129. The reversal of 81869121 is 12196818.

It is not a de Polignac number, because 81869121 - 2⁶ = 81869057 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81869129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 84180 + ... + 85146.

It is an arithmetic number, because the mean of its divisors is an integer number (5159440).

Almost surely, 2^81869121 is an apocalyptic number.

It is an amenable number.

81869121 is a deficient number, since it is larger than the sum of its proper divisors (41957439).

81869121 is a wasteful number, since it uses less digits than its factorization.

81869121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1405 (or 1402 counting only the distinct ones).

The product of its digits is 6912, while the sum is 36.

The square root of 81869121 is about 9048.1556684222. The cubic root of 81869121 is about 434.2168867179.

The spelling of 81869121 in words is "eighty-one million, eight hundred sixty-nine thousand, one hundred twenty-one".