72721 has 6 divisors (see below), whose sum is σ = 80066. Its totient is φ = 66000.

The previous prime is 72719. The next prime is 72727. The reversal of 72721 is 12727.

72721 is nontrivially palindromic in base 16.

It can be written as a sum of positive squares in only one way, i.e., 69696 + 3025 = 264^2 + 55^2 .

It is not a de Polignac number, because 72721 - 2¹ = 72719 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72727) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 180 + ... + 421.

2⁷²⁷²¹ is an apocalyptic number.

It is an amenable number.

72721 is a deficient number, since it is larger than the sum of its proper divisors (7345).

72721 is a wasteful number, since it uses less digits than its factorization.

72721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 623 (or 612 counting only the distinct ones).

The product of its digits is 196, while the sum is 19.

The square root of 72721 is about 269.6683147869. The cubic root of 72721 is about 41.7400803521.

The spelling of 72721 in words is "seventy-two thousand, seven hundred twenty-one", and thus it is an iban number.