81251 has 4 divisors (see below), whose sum is σ = 83904. Its totient is φ = 78600.

The previous prime is 81239. The next prime is 81281. The reversal of 81251 is 15218.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81251 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 81251.

It is not an unprimeable number, because it can be changed into a prime (81281) 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, 1280 + ... + 1341.

It is an arithmetic number, because the mean of its divisors is an integer number (20976).

2⁸¹²⁵¹ is an apocalyptic number.

81251 is a deficient number, since it is larger than the sum of its proper divisors (2653).

81251 is a wasteful number, since it uses less digits than its factorization.

81251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2652.

The product of its digits is 80, while the sum is 17.

The square root of 81251 is about 285.0456103854. The cubic root of 81251 is about 43.3121329564.

Adding to 81251 its reverse (15218), we get a palindrome (96469).

The spelling of 81251 in words is "eighty-one thousand, two hundred fifty-one".