899805821 has 2 divisors, whose sum is σ = 899805822. Its totient is φ = 899805820.

The previous prime is 899805817. The next prime is 899805859. The reversal of 899805821 is 128508998.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 583464025 + 316341796 = 24155^2 + 17786^2 .

It is a cyclic number.

It is not a de Polignac number, because 899805821 - 2² = 899805817 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 899805821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (899805521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 449902910 + 449902911.

It is an arithmetic number, because the mean of its divisors is an integer number (449902911).

Almost surely, 2^899805821 is an apocalyptic number.

It is an amenable number.

899805821 is a deficient number, since it is larger than the sum of its proper divisors (1).

899805821 is an equidigital number, since it uses as much as digits as its factorization.

899805821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 414720, while the sum is 50.

The square root of 899805821 is about 29996.7635087521. The cubic root of 899805821 is about 965.4199434027.

The spelling of 899805821 in words is "eight hundred ninety-nine million, eight hundred five thousand, eight hundred twenty-one".