721957801761 has 45 divisors (see below), whose sum is σ = 1254651595329. Its totient is φ = 412516726776.

The previous prime is 721957801727. The next prime is 721957801769. The reversal of 721957801761 is 167108759127.

The square root of 721957801761 is 849681.

It is a perfect power (a square), and thus also a powerful number.

721957801761 is a `hidden beast` number, since 7 + 2 + 1 + 9 + 578 + 0 + 1 + 7 + 61 = 666.

It is not a de Polignac number, because 721957801761 - 2¹¹ = 721957799713 is a prime.

It is a super-2 number, since 2×721957801761² (a number of 25 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 721957801698 and 721957801707.

It is not an unprimeable number, because it can be changed into a prime (721957801769) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 53523160 + ... + 53536646.

Almost surely, 2^721957801761 is an apocalyptic number.

721957801761 is the 849681-st square number.

721957801761 is the 424841-st centered octagonal number.

It is an amenable number.

721957801761 is a deficient number, since it is larger than the sum of its proper divisors (532693793568).

721957801761 is an frugal number, since it uses more digits than its factorization.

721957801761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27000 (or 13497 counting only the distinct ones).

The product of its (nonzero) digits is 1481760, while the sum is 54.

The spelling of 721957801761 in words is "seven hundred twenty-one billion, nine hundred fifty-seven million, eight hundred one thousand, seven hundred sixty-one".