820449991 has 8 divisors (see below), whose sum is σ = 849099600. Its totient is φ = 791824320.

The previous prime is 820449989. The next prime is 820450003. The reversal of 820449991 is 199944028.

820449991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 820449991 - 2¹ = 820449989 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 (820449191) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 90171 + ... + 98851.

It is an arithmetic number, because the mean of its divisors is an integer number (106137450).

Almost surely, 2^820449991 is an apocalyptic number.

820449991 is a deficient number, since it is larger than the sum of its proper divisors (28649609).

820449991 is a wasteful number, since it uses less digits than its factorization.

820449991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11969.

The product of its (nonzero) digits is 186624, while the sum is 46.

The square root of 820449991 is about 28643.4982325833. The cubic root of 820449991 is about 936.1613452929.

The spelling of 820449991 in words is "eight hundred twenty million, four hundred forty-nine thousand, nine hundred ninety-one".