820666720 has 48 divisors (see below), whose sum is σ = 2001379968. Its totient is φ = 317675520.

The previous prime is 820666711. The next prime is 820666747. The reversal of 820666720 is 27666028.

It is a self number, because there is not a number n which added to its sum of digits gives 820666720.

It is a congruent number.

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, 77769 + ... + 87688.

It is an arithmetic number, because the mean of its divisors is an integer number (41695416).

Almost surely, 2^820666720 is an apocalyptic number.

820666720 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

820666720 is an abundant number, since it is smaller than the sum of its proper divisors (1180713248).

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

820666720 is a wasteful number, since it uses less digits than its factorization.

820666720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165503 (or 165495 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 37.

The square root of 820666720 is about 28647.2811973493. The cubic root of 820666720 is about 936.2437697557.

The spelling of 820666720 in words is "eight hundred twenty million, six hundred sixty-six thousand, seven hundred twenty".