867842561 has 2 divisors, whose sum is σ = 867842562. Its totient is φ = 867842560.

The previous prime is 867842557. The next prime is 867842567. The reversal of 867842561 is 165248768.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 792760336 + 75082225 = 28156^2 + 8665^2 .

It is a cyclic number.

It is not a de Polignac number, because 867842561 - 2² = 867842557 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (867842567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 433921280 + 433921281.

It is an arithmetic number, because the mean of its divisors is an integer number (433921281).

Almost surely, 2^867842561 is an apocalyptic number.

It is an amenable number.

867842561 is a deficient number, since it is larger than the sum of its proper divisors (1).

867842561 is an equidigital number, since it uses as much as digits as its factorization.

867842561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 645120, while the sum is 47.

The square root of 867842561 is about 29459.1676902115. The cubic root of 867842561 is about 953.8505073504.

It can be divided in two parts, 8678425 and 61, that multiplied together give a palindrome (529383925).

The spelling of 867842561 in words is "eight hundred sixty-seven million, eight hundred forty-two thousand, five hundred sixty-one".