81311777 has 4 divisors (see below), whose sum is σ = 82341120. Its totient is φ = 80282436.

The previous prime is 81311743. The next prime is 81311779. The reversal of 81311777 is 77711318.

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 81311777 - 2¹⁶ = 81246241 is a prime.

It is a super-2 number, since 2×81311777² = 13223210157795458, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81311779) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 514553 + ... + 514710.

It is an arithmetic number, because the mean of its divisors is an integer number (20585280).

Almost surely, 2^81311777 is an apocalyptic number.

It is an amenable number.

81311777 is a deficient number, since it is larger than the sum of its proper divisors (1029343).

81311777 is a wasteful number, since it uses less digits than its factorization.

81311777 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1029342.

The product of its digits is 8232, while the sum is 35.

The square root of 81311777 is about 9017.3043089385. The cubic root of 81311777 is about 433.2292964576.

The spelling of 81311777 in words is "eighty-one million, three hundred eleven thousand, seven hundred seventy-seven".