721665834 has 16 divisors (see below), whose sum is σ = 1482341088. Its totient is φ = 234053712.

The previous prime is 721665829. The next prime is 721665839. The reversal of 721665834 is 438566127.

It is an interprime number because it is at equal distance from previous prime (721665829) and next prime (721665839).

It is not an unprimeable number, because it can be changed into a prime (721665839) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1625152 + ... + 1625595.

It is an arithmetic number, because the mean of its divisors is an integer number (92646318).

Almost surely, 2^721665834 is an apocalyptic number.

721665834 is a gapful number since it is divisible by the number (74) formed by its first and last digit.

721665834 is an abundant number, since it is smaller than the sum of its proper divisors (760675254).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

721665834 is a wasteful number, since it uses less digits than its factorization.

721665834 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3250789.

The product of its digits is 241920, while the sum is 42.

The square root of 721665834 is about 26863.8387800404. The cubic root of 721665834 is about 896.9716462019.

The spelling of 721665834 in words is "seven hundred twenty-one million, six hundred sixty-five thousand, eight hundred thirty-four".