72721129 has 4 divisors (see below), whose sum is σ = 78315076. Its totient is φ = 67127184.

The previous prime is 72721123. The next prime is 72721139. The reversal of 72721129 is 92112727.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 92112727 = 7 ⋅13158961.

It can be written as a sum of positive squares in 2 ways, for example, as 6135529 + 66585600 = 2477^2 + 8160^2 .

It is a cyclic number.

It is not a de Polignac number, because 72721129 - 2²¹ = 70623977 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 72721129.

It is not an unprimeable number, because it can be changed into a prime (72721123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2796954 + ... + 2796979.

It is an arithmetic number, because the mean of its divisors is an integer number (19578769).

Almost surely, 2^72721129 is an apocalyptic number.

It is an amenable number.

72721129 is a deficient number, since it is larger than the sum of its proper divisors (5593947).

72721129 is a wasteful number, since it uses less digits than its factorization.

72721129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5593946.

The product of its digits is 3528, while the sum is 31.

The square root of 72721129 is about 8527.6684386765. The cubic root of 72721129 is about 417.4010503308.

The spelling of 72721129 in words is "seventy-two million, seven hundred twenty-one thousand, one hundred twenty-nine".