73072721 has 8 divisors (see below), whose sum is σ = 75826920. Its totient is φ = 70334208.

The previous prime is 73072691. The next prime is 73072723. The reversal of 73072721 is 12727037.

It can be written as a sum of positive squares in 4 ways, for example, as 21520321 + 51552400 = 4639^2 + 7180^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 73072721 - 2²⁶ = 5963857 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (73072723) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6035 + ... + 13511.

It is an arithmetic number, because the mean of its divisors is an integer number (9478365).

Almost surely, 2^73072721 is an apocalyptic number.

It is an amenable number.

73072721 is a deficient number, since it is larger than the sum of its proper divisors (2754199).

73072721 is a wasteful number, since it uses less digits than its factorization.

73072721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7843.

The product of its (nonzero) digits is 4116, while the sum is 29.

The square root of 73072721 is about 8548.2583606253. The cubic root of 73072721 is about 418.0726524510.

Adding to 73072721 its reverse (12727037), we get a palindrome (85799758).

The spelling of 73072721 in words is "seventy-three million, seventy-two thousand, seven hundred twenty-one".