721545135666500 has 48 divisors (see below), whose sum is σ = 1579823983723440. Its totient is φ = 287891056569600.

The previous prime is 721545135666409. The next prime is 721545135666503. The reversal of 721545135666500 is 5666531545127.

It can be written as a sum of positive squares in 8 ways, for example, as 315506193100036 + 406038942566464 = 17762494^2 + 20150408^2 .

It is not an unprimeable number, because it can be changed into a prime (721545135666503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1817295545 + ... + 1817692544.

It is an arithmetic number, because the mean of its divisors is an integer number (32912999660905).

Almost surely, 2^{721545135666500} is an apocalyptic number.

It is an amenable number.

721545135666500 is an abundant number, since it is smaller than the sum of its proper divisors (858278848056940).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

721545135666500 is a wasteful number, since it uses less digits than its factorization.

721545135666500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3634988505 (or 3634988493 counting only the distinct ones).

The product of its (nonzero) digits is 22680000, while the sum is 56.

The spelling of 721545135666500 in words is "seven hundred twenty-one trillion, five hundred forty-five billion, one hundred thirty-five million, six hundred sixty-six thousand, five hundred".