81272137 has 4 divisors (see below), whose sum is σ = 81339076. Its totient is φ = 81205200.

The previous prime is 81272131. The next prime is 81272159. The reversal of 81272137 is 73127218.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 73127218 = 2 ⋅36563609.

It can be written as a sum of positive squares in 2 ways, for example, as 71166096 + 10106041 = 8436^2 + 3179^2 .

It is a cyclic number.

It is not a de Polignac number, because 81272137 - 2²³ = 72883529 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81272099 and 81272108.

It is not an unprimeable number, because it can be changed into a prime (81272131) 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, 31614 + ... + 34087.

It is an arithmetic number, because the mean of its divisors is an integer number (20334769).

Almost surely, 2^81272137 is an apocalyptic number.

It is an amenable number.

81272137 is a deficient number, since it is larger than the sum of its proper divisors (66939).

81272137 is a wasteful number, since it uses less digits than its factorization.

81272137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66938.

The product of its digits is 4704, while the sum is 31.

The square root of 81272137 is about 9015.1060448560. The cubic root of 81272137 is about 433.1588843501.

The spelling of 81272137 in words is "eighty-one million, two hundred seventy-two thousand, one hundred thirty-seven".