724020721 has 2 divisors, whose sum is σ = 724020722. Its totient is φ = 724020720.

The previous prime is 724020677. The next prime is 724020767. The reversal of 724020721 is 127020427.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 699020721 + 25000000 = 26439^2 + 5000^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-724020721 is a prime.

It is not a weakly prime, because it can be changed into another prime (724320721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 362010360 + 362010361.

It is an arithmetic number, because the mean of its divisors is an integer number (362010361).

Almost surely, 2^724020721 is an apocalyptic number.

It is an amenable number.

724020721 is a deficient number, since it is larger than the sum of its proper divisors (1).

724020721 is an equidigital number, since it uses as much as digits as its factorization.

724020721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1568, while the sum is 25.

The square root of 724020721 is about 26907.6331363426. The cubic root of 724020721 is about 897.9462309262.

The spelling of 724020721 in words is "seven hundred twenty-four million, twenty thousand, seven hundred twenty-one".