81293216 has 12 divisors (see below), whose sum is σ = 160046082. Its totient is φ = 40646592.

The previous prime is 81293161. The next prime is 81293237. The reversal of 81293216 is 61239218.

It can be written as a sum of positive squares in only one way, i.e., 67305616 + 13987600 = 8204^2 + 3740^2 .

It is a Harshad number since it is a multiple of its sum of digits (32), and also a Moran number because the ratio is a prime number: 2540413 = 81293216 / (8 + 1 + 2 + 9 + 3 + 2 + 1 + 6).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1270175 + ... + 1270238.

Almost surely, 2^81293216 is an apocalyptic number.

It is an amenable number.

81293216 is a deficient number, since it is larger than the sum of its proper divisors (78752866).

81293216 is a wasteful number, since it uses less digits than its factorization.

81293216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2540423 (or 2540415 counting only the distinct ones).

The product of its digits is 5184, while the sum is 32.

The square root of 81293216 is about 9016.2750623525. The cubic root of 81293216 is about 433.1963296017.

The spelling of 81293216 in words is "eighty-one million, two hundred ninety-three thousand, two hundred sixteen".