820509660 has 144 divisors (see below), whose sum is σ = 2563456896. Its totient is φ = 212317056.

The previous prime is 820509649. The next prime is 820509727. The reversal of 820509660 is 66905028.

It is a super-2 number, since 2×820509660² = 1346472204306631200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1756747 + ... + 1757213.

It is an arithmetic number, because the mean of its divisors is an integer number (17801784).

Almost surely, 2^820509660 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 820509660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1281728448).

820509660 is an abundant number, since it is smaller than the sum of its proper divisors (1742947236).

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

820509660 is a wasteful number, since it uses less digits than its factorization.

820509660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 752 (or 747 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The square root of 820509660 is about 28644.5397938246. The cubic root of 820509660 is about 936.1840395289.

The spelling of 820509660 in words is "eight hundred twenty million, five hundred nine thousand, six hundred sixty".