721938081 has 4 divisors (see below), whose sum is σ = 962584112. Its totient is φ = 481292052.

The previous prime is 721938059. The next prime is 721938089. The reversal of 721938081 is 180839127.

721938081 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 721938081 - 2⁶ = 721938017 is a prime.

It is a super-2 number, since 2×721938081² = 1042389185595925122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721938089) 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, 120323011 + ... + 120323016.

It is an arithmetic number, because the mean of its divisors is an integer number (240646028).

Almost surely, 2^721938081 is an apocalyptic number.

It is an amenable number.

721938081 is a deficient number, since it is larger than the sum of its proper divisors (240646031).

721938081 is a wasteful number, since it uses less digits than its factorization.

721938081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 240646030.

The product of its (nonzero) digits is 24192, while the sum is 39.

The square root of 721938081 is about 26868.9054671008. The cubic root of 721938081 is about 897.0844256108.

The spelling of 721938081 in words is "seven hundred twenty-one million, nine hundred thirty-eight thousand, eighty-one".