721838649 has 24 divisors (see below), whose sum is σ = 1185448608. Its totient is φ = 388214400.

The previous prime is 721838603. The next prime is 721838651. The reversal of 721838649 is 946838127.

It is not a de Polignac number, because 721838649 - 2⁸ = 721838393 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 721838598 and 721838607.

It is not an unprimeable number, because it can be changed into a prime (721838699) 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 23 ways as a sum of consecutive naturals, for example, 141927 + ... + 146924.

It is an arithmetic number, because the mean of its divisors is an integer number (49393692).

Almost surely, 2^721838649 is an apocalyptic number.

It is an amenable number.

721838649 is a deficient number, since it is larger than the sum of its proper divisors (463609959).

721838649 is a wasteful number, since it uses less digits than its factorization.

721838649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 288885 (or 288878 counting only the distinct ones).

The product of its digits is 580608, while the sum is 48.

The square root of 721838649 is about 26867.0550861087. The cubic root of 721838649 is about 897.0432387942.

The spelling of 721838649 in words is "seven hundred twenty-one million, eight hundred thirty-eight thousand, six hundred forty-nine".