821006505 has 96 divisors (see below), whose sum is σ = 1664582400. Its totient is φ = 370275840.

The previous prime is 821006491. The next prime is 821006519. The reversal of 821006505 is 505600128.

821006505 is a `hidden beast` number, since 8 + 2 + 1 + 0 + 0 + 650 + 5 = 666.

821006505 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (821006491) and next prime (821006519).

It is not a de Polignac number, because 821006505 - 2¹⁵ = 820973737 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 420271 + ... + 422219.

It is an arithmetic number, because the mean of its divisors is an integer number (17339400).

Almost surely, 2^821006505 is an apocalyptic number.

It is an amenable number.

821006505 is an abundant number, since it is smaller than the sum of its proper divisors (843575895).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

821006505 is a wasteful number, since it uses less digits than its factorization.

821006505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2031 (or 2028 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

The square root of 821006505 is about 28653.2110765966. The cubic root of 821006505 is about 936.3729645869.

The spelling of 821006505 in words is "eight hundred twenty-one million, six thousand, five hundred five".