81387473 has 2 divisors, whose sum is σ = 81387474. Its totient is φ = 81387472.

The previous prime is 81387443. The next prime is 81387479. The reversal of 81387473 is 37478318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78978769 + 2408704 = 8887^2 + 1552^2 .

It is a cyclic number.

It is not a de Polignac number, because 81387473 - 2¹² = 81383377 is a prime.

It is a super-2 number, since 2×81387473² = 13247841522651458, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81387473.

It is not a weakly prime, because it can be changed into another prime (81387479) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40693736 + 40693737.

It is an arithmetic number, because the mean of its divisors is an integer number (40693737).

Almost surely, 2^81387473 is an apocalyptic number.

It is an amenable number.

81387473 is a deficient number, since it is larger than the sum of its proper divisors (1).

81387473 is an equidigital number, since it uses as much as digits as its factorization.

81387473 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 112896, while the sum is 41.

The square root of 81387473 is about 9021.5005957989. The cubic root of 81387473 is about 433.3636909041.

The spelling of 81387473 in words is "eighty-one million, three hundred eighty-seven thousand, four hundred seventy-three".