721125513 has 12 divisors (see below), whose sum is σ = 1077544260. Its totient is φ = 464172576.

The previous prime is 721125511. The next prime is 721125541. The reversal of 721125513 is 315521127.

721125513 is a `hidden beast` number, since 7 + 21 + 125 + 513 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 282139209 + 438986304 = 16797^2 + 20952^2 .

It is not a de Polignac number, because 721125513 - 2¹ = 721125511 is a prime.

It is not an unprimeable number, because it can be changed into a prime (721125511) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1381206 + ... + 1381727.

It is an arithmetic number, because the mean of its divisors is an integer number (89795355).

Almost surely, 2^721125513 is an apocalyptic number.

It is an amenable number.

721125513 is a deficient number, since it is larger than the sum of its proper divisors (356418747).

721125513 is a wasteful number, since it uses less digits than its factorization.

721125513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2762968 (or 2762965 counting only the distinct ones).

The product of its digits is 2100, while the sum is 27.

The square root of 721125513 is about 26853.7802366818. The cubic root of 721125513 is about 896.7477320302.

The spelling of 721125513 in words is "seven hundred twenty-one million, one hundred twenty-five thousand, five hundred thirteen".