729211661 has 4 divisors (see below), whose sum is σ = 731700732. Its totient is φ = 726722592.

The previous prime is 729211657. The next prime is 729211663. The reversal of 729211661 is 166112927.

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 697963561 + 31248100 = 26419^2 + 5590^2 .

It is a cyclic number.

It is not a de Polignac number, because 729211661 - 2² = 729211657 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (729211663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1244096 + ... + 1244681.

It is an arithmetic number, because the mean of its divisors is an integer number (182925183).

Almost surely, 2^729211661 is an apocalyptic number.

It is an amenable number.

729211661 is a deficient number, since it is larger than the sum of its proper divisors (2489071).

729211661 is a wasteful number, since it uses less digits than its factorization.

729211661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2489070.

The product of its digits is 9072, while the sum is 35.

The square root of 729211661 is about 27003.9193636776. The cubic root of 729211661 is about 900.0870948636.

The spelling of 729211661 in words is "seven hundred twenty-nine million, two hundred eleven thousand, six hundred sixty-one".