721630457 has 4 divisors (see below), whose sum is σ = 735246180. Its totient is φ = 708014736.

The previous prime is 721630373. The next prime is 721630471. The reversal of 721630457 is 754036127.

721630457 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 372837481 + 348792976 = 19309^2 + 18676^2 .

It is a cyclic number.

It is not a de Polignac number, because 721630457 - 2⁸ = 721630201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721630157) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6807782 + ... + 6807887.

It is an arithmetic number, because the mean of its divisors is an integer number (183811545).

Almost surely, 2^721630457 is an apocalyptic number.

It is an amenable number.

721630457 is a deficient number, since it is larger than the sum of its proper divisors (13615723).

721630457 is a wasteful number, since it uses less digits than its factorization.

721630457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13615722.

The product of its (nonzero) digits is 35280, while the sum is 35.

The square root of 721630457 is about 26863.1803217713. The cubic root of 721630457 is about 896.9569890559.

It can be divided in two parts, 7216 and 30457, that added together give a palindrome (37673).

The spelling of 721630457 in words is "seven hundred twenty-one million, six hundred thirty thousand, four hundred fifty-seven".