82771721 has 4 divisors (see below), whose sum is σ = 82980612. Its totient is φ = 82562832.

The previous prime is 82771673. The next prime is 82771723. The reversal of 82771721 is 12717728.

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

It can be written as a sum of positive squares in 2 ways, for example, as 20976400 + 61795321 = 4580^2 + 7861^2 .

It is a cyclic number.

It is not a de Polignac number, because 82771721 - 2¹⁸ = 82509577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (82771723) 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 in 3 ways as a sum of consecutive naturals, for example, 103850 + ... + 104643.

It is an arithmetic number, because the mean of its divisors is an integer number (20745153).

Almost surely, 2^82771721 is an apocalyptic number.

It is an amenable number.

82771721 is a deficient number, since it is larger than the sum of its proper divisors (208891).

82771721 is a wasteful number, since it uses less digits than its factorization.

82771721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208890.

The product of its digits is 10976, while the sum is 35.

The square root of 82771721 is about 9097.8965151292. The cubic root of 82771721 is about 435.8067926746.

The spelling of 82771721 in words is "eighty-two million, seven hundred seventy-one thousand, seven hundred twenty-one".