82789981 has 2 divisors, whose sum is σ = 82789982. Its totient is φ = 82789980.

The previous prime is 82789963. The next prime is 82789991. The reversal of 82789981 is 18998728.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 72097081 + 10692900 = 8491^2 + 3270^2 .

It is a cyclic number.

It is not a de Polignac number, because 82789981 - 2⁷ = 82789853 is a prime.

It is a super-2 number, since 2×82789981² = 13708361907960722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (82789991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41394990 + 41394991.

It is an arithmetic number, because the mean of its divisors is an integer number (41394991).

Almost surely, 2^82789981 is an apocalyptic number.

It is an amenable number.

82789981 is a deficient number, since it is larger than the sum of its proper divisors (1).

82789981 is an equidigital number, since it uses as much as digits as its factorization.

82789981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 580608, while the sum is 52.

The square root of 82789981 is about 9098.8999884601. The cubic root of 82789981 is about 435.8388376243.

The spelling of 82789981 in words is "eighty-two million, seven hundred eighty-nine thousand, nine hundred eighty-one".