721543 has 4 divisors (see below), whose sum is σ = 723600. Its totient is φ = 719488.

The previous prime is 721529. The next prime is 721547. The reversal of 721543 is 345127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 345127 = 269 ⋅1283.

It is a cyclic number.

It is not a de Polignac number, because 721543 - 2¹³ = 713351 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 (721547) 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, 355 + ... + 1252.

It is an arithmetic number, because the mean of its divisors is an integer number (180900).

2⁷²¹⁵⁴³ is an apocalyptic number.

721543 is a deficient number, since it is larger than the sum of its proper divisors (2057).

721543 is a wasteful number, since it uses less digits than its factorization.

721543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2056.

The product of its digits is 840, while the sum is 22.

The square root of 721543 is about 849.4368722866. The cubic root of 721543 is about 89.6920752440.

The spelling of 721543 in words is "seven hundred twenty-one thousand, five hundred forty-three".