721763137 has 4 divisors (see below), whose sum is σ = 722964676. Its totient is φ = 720561600.

The previous prime is 721763113. The next prime is 721763143. The reversal of 721763137 is 731367127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 731367127 = 59 ⋅12396053.

It can be written as a sum of positive squares in 2 ways, for example, as 280931121 + 440832016 = 16761^2 + 20996^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721763137 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 721763096 and 721763105.

It is not an unprimeable number, because it can be changed into a prime (721763737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 599868 + ... + 601069.

It is an arithmetic number, because the mean of its divisors is an integer number (180741169).

Almost surely, 2^721763137 is an apocalyptic number.

It is an amenable number.

721763137 is a deficient number, since it is larger than the sum of its proper divisors (1201539).

721763137 is a wasteful number, since it uses less digits than its factorization.

721763137 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1201538.

The product of its digits is 37044, while the sum is 37.

The square root of 721763137 is about 26865.6497594977. The cubic root of 721763137 is about 897.0119576155.

The spelling of 721763137 in words is "seven hundred twenty-one million, seven hundred sixty-three thousand, one hundred thirty-seven".