721923 has 4 divisors (see below), whose sum is σ = 962568. Its totient is φ = 481280.

The previous prime is 721921. The next prime is 721951. The reversal of 721923 is 329127.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 721923 - 2¹ = 721921 is a prime.

It is a D-number.

It is a junction number, because it is equal to n+sod(n) for n = 721893 and 721902.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721923.

It is not an unprimeable number, because it can be changed into a prime (721921) 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, 120318 + ... + 120323.

It is an arithmetic number, because the mean of its divisors is an integer number (240642).

2⁷²¹⁹²³ is an apocalyptic number.

721923 is a deficient number, since it is larger than the sum of its proper divisors (240645).

721923 is a wasteful number, since it uses less digits than its factorization.

721923 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 240644.

The product of its digits is 756, while the sum is 24.

The square root of 721923 is about 849.6605204433. The cubic root of 721923 is about 89.7078178988.

The spelling of 721923 in words is "seven hundred twenty-one thousand, nine hundred twenty-three".