721123 has 12 divisors (see below), whose sum is σ = 830088. Its totient is φ = 624000.

The previous prime is 721117. The next prime is 721129. The reversal of 721123 is 321127.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (721117) and next prime (721129).

It is not a de Polignac number, because 721123 - 2⁹ = 720611 is a prime.

It is a super-2 number, since 2×721123² = 1040036762258, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 721097 and 721106.

It is not an unprimeable number, because it can be changed into a prime (721129) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2748 + ... + 2998.

It is an arithmetic number, because the mean of its divisors is an integer number (69174).

2⁷²¹¹²³ is an apocalyptic number.

721123 is a deficient number, since it is larger than the sum of its proper divisors (108965).

721123 is a wasteful number, since it uses less digits than its factorization.

721123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 294 (or 281 counting only the distinct ones).

The product of its digits is 84, while the sum is 16.

The square root of 721123 is about 849.1896136906. The cubic root of 721123 is about 89.6746690358.

The spelling of 721123 in words is "seven hundred twenty-one thousand, one hundred twenty-three", and thus it is an iban number.