81228131 has 4 divisors (see below), whose sum is σ = 81275472. Its totient is φ = 81180792.

The previous prime is 81228113. The next prime is 81228143. The reversal of 81228131 is 13182218.

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

It is a cyclic number.

It is not a de Polignac number, because 81228131 - 2¹⁸ = 80965987 is a prime.

It is a super-2 number, since 2×81228131² = 13196018531506322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81228131.

It is not an unprimeable number, because it can be changed into a prime (81228031) 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, 20996 + ... + 24561.

It is an arithmetic number, because the mean of its divisors is an integer number (20318868).

Almost surely, 2^81228131 is an apocalyptic number.

81228131 is a deficient number, since it is larger than the sum of its proper divisors (47341).

81228131 is a wasteful number, since it uses less digits than its factorization.

81228131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47340.

The product of its digits is 768, while the sum is 26.

The square root of 81228131 is about 9012.6650331631. The cubic root of 81228131 is about 433.0806901415.

The spelling of 81228131 in words is "eighty-one million, two hundred twenty-eight thousand, one hundred thirty-one".