721879 has 4 divisors (see below), whose sum is σ = 730080. Its totient is φ = 713680.

The previous prime is 721859. The next prime is 721883. The reversal of 721879 is 978127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 978127 = 73 ⋅13399.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721879 is a prime.

It is a super-2 number, since 2×721879² = 1042218581282, which contains 22 as substring.

It is a Duffinian number.

721879 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3967 + ... + 4144.

It is an arithmetic number, because the mean of its divisors is an integer number (182520).

2⁷²¹⁸⁷⁹ is an apocalyptic number.

721879 is a deficient number, since it is larger than the sum of its proper divisors (8201).

721879 is an equidigital number, since it uses as much as digits as its factorization.

721879 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8200.

The product of its digits is 7056, while the sum is 34.

The square root of 721879 is about 849.6346273546. The cubic root of 721879 is about 89.7059953479.

It can be divided in two parts, 721 and 879, that added together give a square (1600 = 40²).

The spelling of 721879 in words is "seven hundred twenty-one thousand, eight hundred seventy-nine".