729777781 has 8 divisors (see below), whose sum is σ = 737672760. Its totient is φ = 721904832.

The previous prime is 729777773. The next prime is 729777791. The reversal of 729777781 is 187777927.

It can be written as a sum of positive squares in 4 ways, for example, as 13359025 + 716418756 = 3655^2 + 26766^2 .

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 729777781 - 2³ = 729777773 is a prime.

It is a super-2 number, since 2×729777781² = 1065151219282567922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (729777791) 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 7 ways as a sum of consecutive naturals, for example, 66051 + ... + 76303.

It is an arithmetic number, because the mean of its divisors is an integer number (92209095).

Almost surely, 2^729777781 is an apocalyptic number.

It is an amenable number.

729777781 is a deficient number, since it is larger than the sum of its proper divisors (7894979).

729777781 is a wasteful number, since it uses less digits than its factorization.

729777781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11015.

The product of its digits is 2420208, while the sum is 55.

The square root of 729777781 is about 27014.3995121121. The cubic root of 729777781 is about 900.3199607223.

It can be divided in two parts, 7297 and 77781, that added together give a triangular number (85078 = T₄₁₂).

The spelling of 729777781 in words is "seven hundred twenty-nine million, seven hundred seventy-seven thousand, seven hundred eighty-one".