81921141 has 24 divisors (see below), whose sum is σ = 127221120. Its totient is φ = 50633856.

The previous prime is 81921139. The next prime is 81921163. The reversal of 81921141 is 14112918.

It is not a de Polignac number, because 81921141 - 2¹ = 81921139 is a prime.

It is a super-2 number, since 2×81921141² = 13422146685483762, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81921121) 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, 2941 + ... + 13133.

It is an arithmetic number, because the mean of its divisors is an integer number (5300880).

Almost surely, 2^81921141 is an apocalyptic number.

It is an amenable number.

81921141 is a deficient number, since it is larger than the sum of its proper divisors (45299979).

81921141 is a wasteful number, since it uses less digits than its factorization.

81921141 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10265 (or 10262 counting only the distinct ones).

The product of its digits is 576, while the sum is 27.

The square root of 81921141 is about 9051.0298309087. The cubic root of 81921141 is about 434.3088350198.

The spelling of 81921141 in words is "eighty-one million, nine hundred twenty-one thousand, one hundred forty-one".