721851642651 has 4 divisors (see below), whose sum is σ = 962468856872. Its totient is φ = 481234428432.

The previous prime is 721851642649. The next prime is 721851642671. The reversal of 721851642651 is 156246158127.

It is a happy number.

721851642651 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 721851642651 - 2¹ = 721851642649 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 721851642651.

It is not an unprimeable number, because it can be changed into a prime (721851642601) 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, 120308607106 + ... + 120308607111.

It is an arithmetic number, because the mean of its divisors is an integer number (240617214218).

Almost surely, 2^721851642651 is an apocalyptic number.

721851642651 is a deficient number, since it is larger than the sum of its proper divisors (240617214221).

721851642651 is a wasteful number, since it uses less digits than its factorization.

721851642651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 240617214220.

The product of its digits is 806400, while the sum is 48.

The spelling of 721851642651 in words is "seven hundred twenty-one billion, eight hundred fifty-one million, six hundred forty-two thousand, six hundred fifty-one".