721541 has 4 divisors (see below), whose sum is σ = 724800. Its totient is φ = 718284.

The previous prime is 721529. The next prime is 721547. The reversal of 721541 is 145127.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 145127 = 103 ⋅1409.

It is a cyclic number.

It is not a de Polignac number, because 721541 - 2¹⁸ = 459397 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721541.

It is not an unprimeable number, because it can be changed into a prime (721547) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1271 + ... + 1748.

It is an arithmetic number, because the mean of its divisors is an integer number (181200).

2⁷²¹⁵⁴¹ is an apocalyptic number.

It is an amenable number.

721541 is a deficient number, since it is larger than the sum of its proper divisors (3259).

721541 is a wasteful number, since it uses less digits than its factorization.

721541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3258.

The product of its digits is 280, while the sum is 20.

The square root of 721541 is about 849.4356950352. The cubic root of 721541 is about 89.6919923733.

Adding to 721541 its reverse (145127), we get a palindrome (866668).

The spelling of 721541 in words is "seven hundred twenty-one thousand, five hundred forty-one".