821851664 has 40 divisors (see below), whose sum is σ = 1649203968. Its totient is φ = 396339840.

The previous prime is 821851643. The next prime is 821851691. The reversal of 821851664 is 466158128.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 154619 + ... + 159845.

Almost surely, 2^821851664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 821851664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (824601984).

821851664 is an abundant number, since it is smaller than the sum of its proper divisors (827352304).

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

821851664 is a wasteful number, since it uses less digits than its factorization.

821851664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5583 (or 5577 counting only the distinct ones).

The product of its digits is 92160, while the sum is 41.

The square root of 821851664 is about 28667.9553508791. The cubic root of 821851664 is about 936.6941608396.

The spelling of 821851664 in words is "eight hundred twenty-one million, eight hundred fifty-one thousand, six hundred sixty-four".