72726561 has 18 divisors (see below), whose sum is σ = 111596342. Its totient is φ = 45630720.

The previous prime is 72726553. The next prime is 72726611. The reversal of 72726561 is 16562727.

72726561 is a `hidden beast` number, since 72 + 7 + 26 + 561 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 19713600 + 53012961 = 4440^2 + 7281^2 .

It is not a de Polignac number, because 72726561 - 2³ = 72726553 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (72726541) 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 17 ways as a sum of consecutive naturals, for example, 11380 + ... + 16581.

Almost surely, 2^72726561 is an apocalyptic number.

It is an amenable number.

72726561 is a deficient number, since it is larger than the sum of its proper divisors (38869781).

72726561 is a wasteful number, since it uses less digits than its factorization.

72726561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28001 (or 27981 counting only the distinct ones).

The product of its digits is 35280, while the sum is 36.

The square root of 72726561 is about 8527.9869254121. The cubic root of 72726561 is about 417.4114428449.

The spelling of 72726561 in words is "seventy-two million, seven hundred twenty-six thousand, five hundred sixty-one".