81277793 has 2 divisors, whose sum is σ = 81277794. Its totient is φ = 81277792.

The previous prime is 81277787. The next prime is 81277817. The reversal of 81277793 is 39777218.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 73753744 + 7524049 = 8588^2 + 2743^2 .

It is a cyclic number.

It is not a de Polignac number, because 81277793 - 2²⁶ = 14168929 is a prime.

It is a super-3 number, since 3×81277793³ (a number of 25 digits) contains 333 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (81277733) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40638896 + 40638897.

It is an arithmetic number, because the mean of its divisors is an integer number (40638897).

Almost surely, 2^81277793 is an apocalyptic number.

It is an amenable number.

81277793 is a deficient number, since it is larger than the sum of its proper divisors (1).

81277793 is an equidigital number, since it uses as much as digits as its factorization.

81277793 is an evil number, because the sum of its binary digits is even.

The product of its digits is 148176, while the sum is 44.

The square root of 81277793 is about 9015.4197350983. The cubic root of 81277793 is about 433.1689324424.

The spelling of 81277793 in words is "eighty-one million, two hundred seventy-seven thousand, seven hundred ninety-three".