81273965 has 4 divisors (see below), whose sum is σ = 97528764. Its totient is φ = 65019168.

The previous prime is 81273949. The next prime is 81273967. The reversal of 81273965 is 56937218.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 55741156 + 25532809 = 7466^2 + 5053^2 .

It is a cyclic number.

It is not a de Polignac number, because 81273965 - 2⁴ = 81273949 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81273967) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8127392 + ... + 8127401.

It is an arithmetic number, because the mean of its divisors is an integer number (24382191).

Almost surely, 2^81273965 is an apocalyptic number.

It is an amenable number.

81273965 is a deficient number, since it is larger than the sum of its proper divisors (16254799).

81273965 is a wasteful number, since it uses less digits than its factorization.

81273965 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16254798.

The product of its digits is 90720, while the sum is 41.

The square root of 81273965 is about 9015.2074296713. The cubic root of 81273965 is about 433.1621319104.

The spelling of 81273965 in words is "eighty-one million, two hundred seventy-three thousand, nine hundred sixty-five".