81284773 has 4 divisors (see below), whose sum is σ = 81360640. Its totient is φ = 81208908.

The previous prime is 81284729. The next prime is 81284779. The reversal of 81284773 is 37748218.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81284773 - 2²⁵ = 47730341 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81284779) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 36303 + ... + 38476.

It is an arithmetic number, because the mean of its divisors is an integer number (20340160).

Almost surely, 2^81284773 is an apocalyptic number.

It is an amenable number.

81284773 is a deficient number, since it is larger than the sum of its proper divisors (75867).

81284773 is a wasteful number, since it uses less digits than its factorization.

81284773 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75866.

The product of its digits is 75264, while the sum is 40.

The square root of 81284773 is about 9015.8068413204. The cubic root of 81284773 is about 433.1813320270.

The spelling of 81284773 in words is "eighty-one million, two hundred eighty-four thousand, seven hundred seventy-three".