72278561 has 4 divisors (see below), whose sum is σ = 72739092. Its totient is φ = 71818032.

The previous prime is 72278533. The next prime is 72278567. The reversal of 72278561 is 16587227.

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 22505536 + 49773025 = 4744^2 + 7055^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72278561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72278567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 230030 + ... + 230343.

It is an arithmetic number, because the mean of its divisors is an integer number (18184773).

Almost surely, 2^72278561 is an apocalyptic number.

It is an amenable number.

72278561 is a deficient number, since it is larger than the sum of its proper divisors (460531).

72278561 is a wasteful number, since it uses less digits than its factorization.

72278561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 460530.

The product of its digits is 47040, while the sum is 38.

The square root of 72278561 is about 8501.6798928212. The cubic root of 72278561 is about 416.5525836648.

The spelling of 72278561 in words is "seventy-two million, two hundred seventy-eight thousand, five hundred sixty-one".