821017985 has 16 divisors (see below), whose sum is σ = 1023805440. Its totient is φ = 631296960.

The previous prime is 821017973. The next prime is 821017993. The reversal of 821017985 is 589710128.

It is not a de Polignac number, because 821017985 - 2¹⁶ = 820952449 is a prime.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 19640 + ... + 45030.

It is an arithmetic number, because the mean of its divisors is an integer number (63987840).

Almost surely, 2^821017985 is an apocalyptic number.

It is an amenable number.

821017985 is a deficient number, since it is larger than the sum of its proper divisors (202787455).

821017985 is a wasteful number, since it uses less digits than its factorization.

821017985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25648.

The product of its (nonzero) digits is 40320, while the sum is 41.

The square root of 821017985 is about 28653.4114024840. The cubic root of 821017985 is about 936.3773289500.

The spelling of 821017985 in words is "eight hundred twenty-one million, seventeen thousand, nine hundred eighty-five".