721721863 has 2 divisors, whose sum is σ = 721721864. Its totient is φ = 721721862.

The previous prime is 721721851. The next prime is 721721909. The reversal of 721721863 is 368127127.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 721721863 - 2⁵ = 721721831 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721721813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360860931 + 360860932.

It is an arithmetic number, because the mean of its divisors is an integer number (360860932).

Almost surely, 2^721721863 is an apocalyptic number.

721721863 is a deficient number, since it is larger than the sum of its proper divisors (1).

721721863 is an equidigital number, since it uses as much as digits as its factorization.

721721863 is an evil number, because the sum of its binary digits is even.

The product of its digits is 28224, while the sum is 37.

The square root of 721721863 is about 26864.8815928900. The cubic root of 721721863 is about 896.9948587570.

The spelling of 721721863 in words is "seven hundred twenty-one million, seven hundred twenty-one thousand, eight hundred sixty-three".