72820661 has 2 divisors, whose sum is σ = 72820662. Its totient is φ = 72820660.

The previous prime is 72820651. The next prime is 72820729. The reversal of 72820661 is 16602827.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 39250225 + 33570436 = 6265^2 + 5794^2 .

It is a cyclic number.

It is not a de Polignac number, because 72820661 - 2²² = 68626357 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72820651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36410330 + 36410331.

It is an arithmetic number, because the mean of its divisors is an integer number (36410331).

Almost surely, 2^72820661 is an apocalyptic number.

It is an amenable number.

72820661 is a deficient number, since it is larger than the sum of its proper divisors (1).

72820661 is an equidigital number, since it uses as much as digits as its factorization.

72820661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 72820661 is about 8533.5022704632. The cubic root of 72820661 is about 417.5913930940.

The spelling of 72820661 in words is "seventy-two million, eight hundred twenty thousand, six hundred sixty-one".