820621664 has 48 divisors (see below), whose sum is σ = 1656184320. Its totient is φ = 400133760.

The previous prime is 820621639. The next prime is 820621679. The reversal of 820621664 is 466126028.

It is a super-2 number, since 2×820621664² = 1346839830852257792, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 207869 + ... + 211779.

It is an arithmetic number, because the mean of its divisors is an integer number (34503840).

Almost surely, 2^820621664 is an apocalyptic number.

It is an amenable number.

820621664 is an abundant number, since it is smaller than the sum of its proper divisors (835562656).

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

820621664 is a wasteful number, since it uses less digits than its factorization.

820621664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4083 (or 4075 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 35.

The square root of 820621664 is about 28646.4947943025. The cubic root of 820621664 is about 936.2266356499.

The spelling of 820621664 in words is "eight hundred twenty million, six hundred twenty-one thousand, six hundred sixty-four".