728720831 has 4 divisors (see below), whose sum is σ = 728821200. Its totient is φ = 728620464.

The previous prime is 728720819. The next prime is 728720833. The reversal of 728720831 is 138027827.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 138027827 = 7 ⋅19718261.

It is a cyclic number.

It is not a de Polignac number, because 728720831 - 2⁶ = 728720767 is a prime.

It is a super-2 number, since 2×728720831² = 1062068099066661122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (728720833) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38366 + ... + 54123.

It is an arithmetic number, because the mean of its divisors is an integer number (182205300).

Almost surely, 2^728720831 is an apocalyptic number.

728720831 is a deficient number, since it is larger than the sum of its proper divisors (100369).

728720831 is an equidigital number, since it uses as much as digits as its factorization.

728720831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100368.

The product of its (nonzero) digits is 37632, while the sum is 38.

The square root of 728720831 is about 26994.8297086683. The cubic root of 728720831 is about 899.8851009698.

The spelling of 728720831 in words is "seven hundred twenty-eight million, seven hundred twenty thousand, eight hundred thirty-one".