81777338 has 4 divisors (see below), whose sum is σ = 122666010. Its totient is φ = 40888668.

The previous prime is 81777337. The next prime is 81777341. The reversal of 81777338 is 83377718.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 81234169 + 543169 = 9013^2 + 737^2 .

It is not an unprimeable number, because it can be changed into a prime (81777337) 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, 20444333 + ... + 20444336.

Almost surely, 2^81777338 is an apocalyptic number.

81777338 is a deficient number, since it is larger than the sum of its proper divisors (40888672).

81777338 is a wasteful number, since it uses less digits than its factorization.

81777338 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40888671.

The product of its digits is 197568, while the sum is 44.

The square root of 81777338 is about 9043.0823284984. The cubic root of 81777338 is about 434.0545600247.

The spelling of 81777338 in words is "eighty-one million, seven hundred seventy-seven thousand, three hundred thirty-eight".