721855423 has 4 divisors (see below), whose sum is σ = 721984648. Its totient is φ = 721726200.

The previous prime is 721855417. The next prime is 721855439. The reversal of 721855423 is 324558127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 324558127 = 31 ⋅10469617.

It is a cyclic number.

It is not a de Polignac number, because 721855423 - 2¹⁷ = 721724351 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721855493) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55836 + ... + 67537.

It is an arithmetic number, because the mean of its divisors is an integer number (180496162).

Almost surely, 2^721855423 is an apocalyptic number.

721855423 is a deficient number, since it is larger than the sum of its proper divisors (129225).

721855423 is a wasteful number, since it uses less digits than its factorization.

721855423 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129224.

The product of its digits is 67200, while the sum is 37.

The square root of 721855423 is about 26867.3672509980. The cubic root of 721855423 is about 897.0501872014.

The spelling of 721855423 in words is "seven hundred twenty-one million, eight hundred fifty-five thousand, four hundred twenty-three".