81777533 has 2 divisors, whose sum is σ = 81777534. Its totient is φ = 81777532.

The previous prime is 81777461. The next prime is 81777541. The reversal of 81777533 is 33577718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 56957209 + 24820324 = 7547^2 + 4982^2 .

It is a cyclic number.

It is not a de Polignac number, because 81777533 - 2²⁰ = 80728957 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81777233) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40888766 + 40888767.

It is an arithmetic number, because the mean of its divisors is an integer number (40888767).

Almost surely, 2^81777533 is an apocalyptic number.

It is an amenable number.

81777533 is a deficient number, since it is larger than the sum of its proper divisors (1).

81777533 is an equidigital number, since it uses as much as digits as its factorization.

81777533 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 123480, while the sum is 41.

The square root of 81777533 is about 9043.0931102140. The cubic root of 81777533 is about 434.0549050289.

The spelling of 81777533 in words is "eighty-one million, seven hundred seventy-seven thousand, five hundred thirty-three".