81954115 has 4 divisors (see below), whose sum is σ = 98344944. Its totient is φ = 65563288.

The previous prime is 81954109. The next prime is 81954179. The reversal of 81954115 is 51145918.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 51145918 = 2 ⋅25572959.

It is a cyclic number.

It is not a de Polignac number, because 81954115 - 2¹⁹ = 81429827 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 8195407 + ... + 8195416.

It is an arithmetic number, because the mean of its divisors is an integer number (24586236).

Almost surely, 2^81954115 is an apocalyptic number.

81954115 is a deficient number, since it is larger than the sum of its proper divisors (16390829).

81954115 is a wasteful number, since it uses less digits than its factorization.

81954115 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16390828.

The product of its digits is 7200, while the sum is 34.

The square root of 81954115 is about 9052.8512083211. The cubic root of 81954115 is about 434.3670982811.

The spelling of 81954115 in words is "eighty-one million, nine hundred fifty-four thousand, one hundred fifteen".