81512105 has 4 divisors (see below), whose sum is σ = 97814532. Its totient is φ = 65209680.

The previous prime is 81512009. The next prime is 81512117. The reversal of 81512105 is 50121518.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50121518 = 2 ⋅25060759.

It can be written as a sum of positive squares in 2 ways, for example, as 32959081 + 48553024 = 5741^2 + 6968^2 .

It is not a de Polignac number, because 81512105 - 2¹⁴ = 81495721 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8151206 + ... + 8151215.

It is an arithmetic number, because the mean of its divisors is an integer number (24453633).

Almost surely, 2^81512105 is an apocalyptic number.

It is an amenable number.

81512105 is a deficient number, since it is larger than the sum of its proper divisors (16302427).

81512105 is a wasteful number, since it uses less digits than its factorization.

81512105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16302426.

The product of its (nonzero) digits is 400, while the sum is 23.

The square root of 81512105 is about 9028.4054516841. The cubic root of 81512105 is about 433.5847873260.

The spelling of 81512105 in words is "eighty-one million, five hundred twelve thousand, one hundred five".