747730721 has 4 divisors (see below), whose sum is σ = 748046100. Its totient is φ = 747415344.

The previous prime is 747730717. The next prime is 747730747. The reversal of 747730721 is 127037747.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 127037747 = 509 ⋅249583.

It can be written as a sum of positive squares in 2 ways, for example, as 328914496 + 418816225 = 18136^2 + 20465^2 .

It is a cyclic number.

It is not a de Polignac number, because 747730721 - 2² = 747730717 is a prime.

It is a super-2 number, since 2×747730721² = 1118202462254359682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (747730421) 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, 154106 + ... + 158883.

It is an arithmetic number, because the mean of its divisors is an integer number (187011525).

Almost surely, 2^747730721 is an apocalyptic number.

It is an amenable number.

747730721 is a deficient number, since it is larger than the sum of its proper divisors (315379).

747730721 is a wasteful number, since it uses less digits than its factorization.

747730721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 315378.

The product of its (nonzero) digits is 57624, while the sum is 38.

The square root of 747730721 is about 27344.6653115375. The cubic root of 747730721 is about 907.6430254177.

The spelling of 747730721 in words is "seven hundred forty-seven million, seven hundred thirty thousand, seven hundred twenty-one".