1000006561 has 4 divisors (see below), whose sum is σ = 1000074132. Its totient is φ = 999938992.

The previous prime is 1000006541. The next prime is 1000006571. The reversal of 1000006561 is 1656000001.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1656000001 = 61 ⋅27147541.

It can be written as a sum of positive squares in 2 ways, for example, as 834112161 + 165894400 = 28881^2 + 12880^2 .

It is a cyclic number.

It is not a de Polignac number, because 1000006561 - 2¹³ = 999998369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1000006541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 946 + ... + 44731.

It is an arithmetic number, because the mean of its divisors is an integer number (250018533).

Almost surely, 2^1000006561 is an apocalyptic number.

It is an amenable number.

1000006561 is a deficient number, since it is larger than the sum of its proper divisors (67571).

1000006561 is an equidigital number, since it uses as much as digits as its factorization.

1000006561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67570.

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 1000006561 is about 31622.8803400323. The cubic root of 1000006561 is about 1000.0021869952.

Adding to 1000006561 its reverse (1656000001), we get a palindrome (2656006562).

The spelling of 1000006561 in words is "one billion, six thousand, five hundred sixty-one".