82009781 has 6 divisors (see below), whose sum is σ = 95399190. Its totient is φ = 70294056.

The previous prime is 82009703. The next prime is 82009813. The reversal of 82009781 is 18790028.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 45346756 + 36663025 = 6734^2 + 6055^2 .

It is not a de Polignac number, because 82009781 - 2¹⁰ = 82008757 is a prime.

It is a super-2 number, since 2×82009781² = 13451208359335922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (82009181) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 836786 + ... + 836883.

It is an arithmetic number, because the mean of its divisors is an integer number (15899865).

Almost surely, 2^82009781 is an apocalyptic number.

It is an amenable number.

82009781 is a deficient number, since it is larger than the sum of its proper divisors (13389409).

82009781 is a wasteful number, since it uses less digits than its factorization.

82009781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1673683 (or 1673676 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 35.

The square root of 82009781 is about 9055.9251874118. The cubic root of 82009781 is about 434.4654216191.

The spelling of 82009781 in words is "eighty-two million, nine thousand, seven hundred eighty-one".