721100249 has 4 divisors (see below), whose sum is σ = 723561636. Its totient is φ = 718638864.

The previous prime is 721100243. The next prime is 721100267. The reversal of 721100249 is 942001127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 942001127 = 17 ⋅55411831.

It can be written as a sum of positive squares in 2 ways, for example, as 673765849 + 47334400 = 25957^2 + 6880^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721100249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721100243) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1230254 + ... + 1230839.

It is an arithmetic number, because the mean of its divisors is an integer number (180890409).

Almost surely, 2^721100249 is an apocalyptic number.

It is an amenable number.

721100249 is a deficient number, since it is larger than the sum of its proper divisors (2461387).

721100249 is a wasteful number, since it uses less digits than its factorization.

721100249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2461386.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 721100249 is about 26853.3098332403. The cubic root of 721100249 is about 896.7372596510.

The spelling of 721100249 in words is "seven hundred twenty-one million, one hundred thousand, two hundred forty-nine".