81776473 has 4 divisors (see below), whose sum is σ = 82191780. Its totient is φ = 81361168.

The previous prime is 81776447. The next prime is 81776483. The reversal of 81776473 is 37467718.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 37467718 = 2 ⋅18733859.

It can be written as a sum of positive squares in 2 ways, for example, as 42876304 + 38900169 = 6548^2 + 6237^2 .

It is a cyclic number.

It is not a de Polignac number, because 81776473 - 2⁵ = 81776441 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81776413) 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, 207358 + ... + 207751.

It is an arithmetic number, because the mean of its divisors is an integer number (20547945).

Almost surely, 2^81776473 is an apocalyptic number.

It is an amenable number.

81776473 is a deficient number, since it is larger than the sum of its proper divisors (415307).

81776473 is a wasteful number, since it uses less digits than its factorization.

81776473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 415306.

The product of its digits is 197568, while the sum is 43.

The square root of 81776473 is about 9043.0345017588. The cubic root of 81776473 is about 434.0530296149.

The spelling of 81776473 in words is "eighty-one million, seven hundred seventy-six thousand, four hundred seventy-three".