721137818641 has 4 divisors (see below), whose sum is σ = 721157520384. Its totient is φ = 721118116900.

The previous prime is 721137818617. The next prime is 721137818683. The reversal of 721137818641 is 146818731127.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 721137818641 - 2¹¹ = 721137816593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721137812641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9795865 + ... + 9869206.

It is an arithmetic number, because the mean of its divisors is an integer number (180289380096).

Almost surely, 2^721137818641 is an apocalyptic number.

It is an amenable number.

721137818641 is a deficient number, since it is larger than the sum of its proper divisors (19701743).

721137818641 is a wasteful number, since it uses less digits than its factorization.

721137818641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19701742.

The product of its digits is 451584, while the sum is 49.

The spelling of 721137818641 in words is "seven hundred twenty-one billion, one hundred thirty-seven million, eight hundred eighteen thousand, six hundred forty-one".