81142289 has 4 divisors (see below), whose sum is σ = 81945780. Its totient is φ = 80338800.

The previous prime is 81142253. The next prime is 81142291. The reversal of 81142289 is 98224118.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 98224118 = 2 ⋅49112059.

It can be written as a sum of positive squares in 2 ways, for example, as 75829264 + 5313025 = 8708^2 + 2305^2 .

It is a cyclic number.

It is not a de Polignac number, because 81142289 - 2¹⁶ = 81076753 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81142219) 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, 401594 + ... + 401795.

It is an arithmetic number, because the mean of its divisors is an integer number (20486445).

Almost surely, 2^81142289 is an apocalyptic number.

It is an amenable number.

81142289 is a deficient number, since it is larger than the sum of its proper divisors (803491).

81142289 is a wasteful number, since it uses less digits than its factorization.

81142289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 803490.

The product of its digits is 9216, while the sum is 35.

The square root of 81142289 is about 9007.9014759266. The cubic root of 81142289 is about 432.9280762793.

The spelling of 81142289 in words is "eighty-one million, one hundred forty-two thousand, two hundred eighty-nine".