721989523 has 4 divisors (see below), whose sum is σ = 723408480. Its totient is φ = 720570568.

The previous prime is 721989503. The next prime is 721989529. The reversal of 721989523 is 325989127.

721989523 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 an emirpimes, since its reverse is a distinct semiprime: 325989127 = 17 ⋅19175831.

It is a cyclic number.

It is not a de Polignac number, because 721989523 - 2¹³ = 721981331 is a prime.

It is a super-3 number, since 3×721989523³ (a number of 28 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721989529) 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, 708715 + ... + 709732.

It is an arithmetic number, because the mean of its divisors is an integer number (180852120).

Almost surely, 2^721989523 is an apocalyptic number.

721989523 is a deficient number, since it is larger than the sum of its proper divisors (1418957).

721989523 is a wasteful number, since it uses less digits than its factorization.

721989523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1418956.

The product of its digits is 272160, while the sum is 46.

The square root of 721989523 is about 26869.8627275987. The cubic root of 721989523 is about 897.1057324801.

The spelling of 721989523 in words is "seven hundred twenty-one million, nine hundred eighty-nine thousand, five hundred twenty-three".