72706561 has 2 divisors, whose sum is σ = 72706562. Its totient is φ = 72706560.

The previous prime is 72706549. The next prime is 72706583. The reversal of 72706561 is 16560727.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 58599025 + 14107536 = 7655^2 + 3756^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72706561 is a prime.

It is not a weakly prime, because it can be changed into another prime (72706531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36353280 + 36353281.

It is an arithmetic number, because the mean of its divisors is an integer number (36353281).

Almost surely, 2^72706561 is an apocalyptic number.

It is an amenable number.

72706561 is a deficient number, since it is larger than the sum of its proper divisors (1).

72706561 is an equidigital number, since it uses as much as digits as its factorization.

72706561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17640, while the sum is 34.

The square root of 72706561 is about 8526.8142351056. The cubic root of 72706561 is about 417.3731762468.

It can be divided in two parts, 7270 and 6561, that added together give a palindrome (13831).

The spelling of 72706561 in words is "seventy-two million, seven hundred six thousand, five hundred sixty-one".