81457129 has 4 divisors (see below), whose sum is σ = 87723076. Its totient is φ = 75191184.

The previous prime is 81457127. The next prime is 81457133. The reversal of 81457129 is 92175418.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 92175418 = 2 ⋅46087709.

It can be written as a sum of positive squares in 2 ways, for example, as 54051904 + 27405225 = 7352^2 + 5235^2 .

It is a cyclic number.

It is not a de Polignac number, because 81457129 - 2¹ = 81457127 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81457127) 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, 3132954 + ... + 3132979.

It is an arithmetic number, because the mean of its divisors is an integer number (21930769).

Almost surely, 2^81457129 is an apocalyptic number.

It is an amenable number.

81457129 is a deficient number, since it is larger than the sum of its proper divisors (6265947).

81457129 is a wasteful number, since it uses less digits than its factorization.

81457129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6265946.

The product of its digits is 20160, while the sum is 37.

The square root of 81457129 is about 9025.3603252169. The cubic root of 81457129 is about 433.4872880315.

The spelling of 81457129 in words is "eighty-one million, four hundred fifty-seven thousand, one hundred twenty-nine".