721951 has 2 divisors, whose sum is σ = 721952. Its totient is φ = 721950.

The previous prime is 721921. The next prime is 721961. The reversal of 721951 is 159127.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 721951 - 2⁹ = 721439 is a prime.

It is an Ulam number.

721951 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360975 + 360976.

It is an arithmetic number, because the mean of its divisors is an integer number (360976).

2⁷²¹⁹⁵¹ is an apocalyptic number.

721951 is a deficient number, since it is larger than the sum of its proper divisors (1).

721951 is an equidigital number, since it uses as much as digits as its factorization.

721951 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 630, while the sum is 25.

The square root of 721951 is about 849.6769974526. The cubic root of 721951 is about 89.7089776654.

The spelling of 721951 in words is "seven hundred twenty-one thousand, nine hundred fifty-one".