745890721 has 9 divisors (see below), whose sum is σ = 771603699. Its totient is φ = 721010400.

The previous prime is 745890709. The next prime is 745890731. The reversal of 745890721 is 127098547.

The square root of 745890721 is 27311.

It is a perfect power (a square), and thus also a powerful number.

745890721 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 only one way, i.e., 130850721 + 615040000 = 11439^2 + 24800^2 .

It is not a de Polignac number, because 745890721 - 2¹⁷ = 745759649 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (745890731) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 846201 + ... + 847081.

Almost surely, 2^745890721 is an apocalyptic number.

745890721 is the 27311-st square number.

745890721 is the 13656-th centered octagonal number.

It is an amenable number.

745890721 is a deficient number, since it is larger than the sum of its proper divisors (25712978).

745890721 is an frugal number, since it uses more digits than its factorization.

745890721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1824 (or 912 counting only the distinct ones).

The product of its (nonzero) digits is 141120, while the sum is 43.

The cubic root of 745890721 is about 906.8979109528.

The spelling of 745890721 in words is "seven hundred forty-five million, eight hundred ninety thousand, seven hundred twenty-one".