721979 has 2 divisors, whose sum is σ = 721980. Its totient is φ = 721978.

The previous prime is 721961. The next prime is 721991. The reversal of 721979 is 979127.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 721979 - 2¹² = 717883 is a prime.

It is not a weakly prime, because it can be changed into another prime (721909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360989 + 360990.

It is an arithmetic number, because the mean of its divisors is an integer number (360990).

2⁷²¹⁹⁷⁹ is an apocalyptic number.

721979 is a deficient number, since it is larger than the sum of its proper divisors (1).

721979 is an equidigital number, since it uses as much as digits as its factorization.

721979 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7938, while the sum is 35.

The square root of 721979 is about 849.6934741423. The cubic root of 721979 is about 89.7101374019.

The spelling of 721979 in words is "seven hundred twenty-one thousand, nine hundred seventy-nine".