82156561 has 2 divisors, whose sum is σ = 82156562. Its totient is φ = 82156560.

The previous prime is 82156511. The next prime is 82156619. The reversal of 82156561 is 16565128.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 78216336 + 3940225 = 8844^2 + 1985^2 .

It is a cyclic number.

It is not a de Polignac number, because 82156561 - 2¹⁹ = 81632273 is a prime.

It is not a weakly prime, because it can be changed into another prime (82156511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41078280 + 41078281.

It is an arithmetic number, because the mean of its divisors is an integer number (41078281).

Almost surely, 2^82156561 is an apocalyptic number.

It is an amenable number.

82156561 is a deficient number, since it is larger than the sum of its proper divisors (1).

82156561 is an equidigital number, since it uses as much as digits as its factorization.

82156561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14400, while the sum is 34.

The square root of 82156561 is about 9064.0256508904. The cubic root of 82156561 is about 434.7244672525.

The spelling of 82156561 in words is "eighty-two million, one hundred fifty-six thousand, five hundred sixty-one".