721800397 has 2 divisors, whose sum is σ = 721800398. Its totient is φ = 721800396.

The previous prime is 721800383. The next prime is 721800419. The reversal of 721800397 is 793008127.

721800397 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 478253161 + 243547236 = 21869^2 + 15606^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721800397 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721800097) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360900198 + 360900199.

It is an arithmetic number, because the mean of its divisors is an integer number (360900199).

Almost surely, 2^721800397 is an apocalyptic number.

It is an amenable number.

721800397 is a deficient number, since it is larger than the sum of its proper divisors (1).

721800397 is an equidigital number, since it uses as much as digits as its factorization.

721800397 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 21168, while the sum is 37.

The square root of 721800397 is about 26866.3432011132. The cubic root of 721800397 is about 897.0273930073.

It can be divided in two parts, 7218003 and 97, that added together give a triangular number (7218100 = T₃₇₉₉).

The spelling of 721800397 in words is "seven hundred twenty-one million, eight hundred thousand, three hundred ninety-seven".