81777145 has 16 divisors (see below), whose sum is σ = 100358352. Its totient is φ = 63947520.

The previous prime is 81777131. The next prime is 81777151. The reversal of 81777145 is 54177718.

It can be written as a sum of positive squares in 8 ways, for example, as 1296 + 81775849 = 36^2 + 9043^2 .

It is a de Polignac number, because none of the positive numbers 2^k-81777145 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81777098 and 81777107.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 111199 + ... + 111931.

It is an arithmetic number, because the mean of its divisors is an integer number (6272397).

Almost surely, 2^81777145 is an apocalyptic number.

It is an amenable number.

81777145 is a deficient number, since it is larger than the sum of its proper divisors (18581207).

81777145 is a wasteful number, since it uses less digits than its factorization.

81777145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1212.

The product of its digits is 54880, while the sum is 40.

The square root of 81777145 is about 9043.0716573518. The cubic root of 81777145 is about 434.0542185585.

The spelling of 81777145 in words is "eighty-one million, seven hundred seventy-seven thousand, one hundred forty-five".