861721829 has 8 divisors (see below), whose sum is σ = 880502400. Its totient is φ = 842959936.

The previous prime is 861721739. The next prime is 861721871. The reversal of 861721829 is 928127168.

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 861721829 - 2²⁴ = 844944613 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 861721829.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861721129) 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 7 ways as a sum of consecutive naturals, for example, 130397 + ... + 136845.

It is an arithmetic number, because the mean of its divisors is an integer number (110062800).

Almost surely, 2^861721829 is an apocalyptic number.

It is an amenable number.

861721829 is a deficient number, since it is larger than the sum of its proper divisors (18780571).

861721829 is a wasteful number, since it uses less digits than its factorization.

861721829 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9339.

The product of its digits is 96768, while the sum is 44.

The square root of 861721829 is about 29355.0988586310. The cubic root of 861721829 is about 951.6027714074.

The spelling of 861721829 in words is "eight hundred sixty-one million, seven hundred twenty-one thousand, eight hundred twenty-nine".