721735600981 has 4 divisors (see below), whose sum is σ = 739338908364. Its totient is φ = 704132293600.

The previous prime is 721735600931. The next prime is 721735601009. The reversal of 721735600981 is 189006537127.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 92862810756 + 628872790225 = 304734^2 + 793015^2 .

It is a cyclic number.

It is not a de Polignac number, because 721735600981 - 2¹⁷ = 721735469909 is a prime.

It is a super-2 number, since 2×721735600981² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721735600931) 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, 8801653630 + ... + 8801653711.

It is an arithmetic number, because the mean of its divisors is an integer number (184834727091).

Almost surely, 2^721735600981 is an apocalyptic number.

It is an amenable number.

721735600981 is a deficient number, since it is larger than the sum of its proper divisors (17603307383).

721735600981 is a wasteful number, since it uses less digits than its factorization.

721735600981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17603307382.

The product of its (nonzero) digits is 635040, while the sum is 49.

The spelling of 721735600981 in words is "seven hundred twenty-one billion, seven hundred thirty-five million, six hundred thousand, nine hundred eighty-one".