747721 has 8 divisors (see below), whose sum is σ = 813960. Its totient is φ = 682752.

The previous prime is 747713. The next prime is 747731. The reversal of 747721 is 127747.

747721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 1225 + 746496 = 35^2 + 864^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 747721 - 2³ = 747713 is a prime.

It is a Duffinian number.

747721 is a lucky number.

It is a nialpdrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 747721.

It is not an unprimeable number, because it can be changed into a prime (747731) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1215 + ... + 1723.

It is an arithmetic number, because the mean of its divisors is an integer number (101745).

2⁷⁴⁷⁷²¹ is an apocalyptic number.

It is an amenable number.

747721 is a deficient number, since it is larger than the sum of its proper divisors (66239).

747721 is a wasteful number, since it uses less digits than its factorization.

747721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 635.

The product of its digits is 2744, while the sum is 28.

The square root of 747721 is about 864.7086214442. The cubic root of 747721 is about 90.7639092078.

The spelling of 747721 in words is "seven hundred forty-seven thousand, seven hundred twenty-one", and thus it is an iban number.