725161807781 has 4 divisors (see below), whose sum is σ = 725163929964. Its totient is φ = 725159685600.

The previous prime is 725161807771. The next prime is 725161807807. The reversal of 725161807781 is 187708161527.

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 237666000100 + 487495807681 = 487510^2 + 698209^2 .

It is a cyclic number.

It is not a de Polignac number, because 725161807781 - 2⁶ = 725161807717 is a prime.

It is a super-2 number, since 2×725161807781² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (725161807771) 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 3 ways as a sum of consecutive naturals, for example, 419030 + ... + 1275111.

It is an arithmetic number, because the mean of its divisors is an integer number (181290982491).

Almost surely, 2^725161807781 is an apocalyptic number.

It is an amenable number.

725161807781 is a deficient number, since it is larger than the sum of its proper divisors (2122183).

725161807781 is a wasteful number, since it uses less digits than its factorization.

725161807781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2122182.

The product of its (nonzero) digits is 1317120, while the sum is 53.

The spelling of 725161807781 in words is "seven hundred twenty-five billion, one hundred sixty-one million, eight hundred seven thousand, seven hundred eighty-one".