721457 has 4 divisors (see below), whose sum is σ = 787056. Its totient is φ = 655860.

The previous prime is 721451. The next prime is 721481. The reversal of 721457 is 754127.

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.

It is a cyclic number.

It is not a de Polignac number, because 721457 - 2¹⁴ = 705073 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721451) 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, 32783 + ... + 32804.

It is an arithmetic number, because the mean of its divisors is an integer number (196764).

2⁷²¹⁴⁵⁷ is an apocalyptic number.

It is an amenable number.

721457 is a deficient number, since it is larger than the sum of its proper divisors (65599).

721457 is a wasteful number, since it uses less digits than its factorization.

721457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65598.

The product of its digits is 1960, while the sum is 26.

The square root of 721457 is about 849.3862490057. The cubic root of 721457 is about 89.6885116657.

The spelling of 721457 in words is "seven hundred twenty-one thousand, four hundred fifty-seven".