82001581 has 2 divisors, whose sum is σ = 82001582. Its totient is φ = 82001580.

The previous prime is 82001573. The next prime is 82001627. The reversal of 82001581 is 18510028.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62948356 + 19053225 = 7934^2 + 4365^2 .

It is a cyclic number.

It is not a de Polignac number, because 82001581 - 2³ = 82001573 is a prime.

It is a super-2 number, since 2×82001581² = 13448518572999122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (82001281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41000790 + 41000791.

It is an arithmetic number, because the mean of its divisors is an integer number (41000791).

Almost surely, 2^82001581 is an apocalyptic number.

It is an amenable number.

82001581 is a deficient number, since it is larger than the sum of its proper divisors (1).

82001581 is an equidigital number, since it uses as much as digits as its factorization.

82001581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 640, while the sum is 25.

The square root of 82001581 is about 9055.4724338380. The cubic root of 82001581 is about 434.4509406830.

The spelling of 82001581 in words is "eighty-two million, one thousand, five hundred eighty-one".