80644561 has 4 divisors (see below), whose sum is σ = 81443124. Its totient is φ = 79846000.

The previous prime is 80644541. The next prime is 80644567. The reversal of 80644561 is 16544608.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 63504961 + 17139600 = 7969^2 + 4140^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-80644561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (80644567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 399130 + ... + 399331.

It is an arithmetic number, because the mean of its divisors is an integer number (20360781).

Almost surely, 2^80644561 is an apocalyptic number.

It is an amenable number.

80644561 is a deficient number, since it is larger than the sum of its proper divisors (798563).

80644561 is a wasteful number, since it uses less digits than its factorization.

80644561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 798562.

The product of its (nonzero) digits is 23040, while the sum is 34.

The square root of 80644561 is about 8980.2316785259. The cubic root of 80644561 is about 432.0410644121.

The spelling of 80644561 in words is "eighty million, six hundred forty-four thousand, five hundred sixty-one".