721697644121 has 8 divisors (see below), whose sum is σ = 751642467264. Its totient is φ = 692302267440.

The previous prime is 721697644099. The next prime is 721697644123. The reversal of 721697644121 is 121446796127.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 721697644121 - 2²⁶ = 721630535257 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 721697644121.

It is not an unprimeable number, because it can be changed into a prime (721697644123) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 137358935 + ... + 137364188.

It is an arithmetic number, because the mean of its divisors is an integer number (93955308408).

Almost surely, 2^721697644121 is an apocalyptic number.

721697644121 is a gapful number since it is divisible by the number (71) formed by its first and last digit.

It is an amenable number.

721697644121 is a deficient number, since it is larger than the sum of its proper divisors (29944823143).

721697644121 is a wasteful number, since it uses less digits than its factorization.

721697644121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 274723231.

The product of its digits is 1016064, while the sum is 50.

The spelling of 721697644121 in words is "seven hundred twenty-one billion, six hundred ninety-seven million, six hundred forty-four thousand, one hundred twenty-one".