1605320220 has 48 divisors (see below), whose sum is σ = 5137026048. Its totient is φ = 366930240.

The previous prime is 1605320209. The next prime is 1605320237. The reversal of 1605320220 is 220235061.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1910676 + ... + 1911515.

It is an arithmetic number, because the mean of its divisors is an integer number (107021376).

Almost surely, 2^1605320220 is an apocalyptic number.

1605320220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1605320220 is an abundant number, since it is smaller than the sum of its proper divisors (3531705828).

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

1605320220 is a wasteful number, since it uses less digits than its factorization.

1605320220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3822210 (or 3822208 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 1605320220 is about 40066.4475590237. The cubic root of 1605320220 is about 1170.9020292038.

Adding to 1605320220 its reverse (220235061), we get a palindrome (1825555281).

The spelling of 1605320220 in words is "one billion, six hundred five million, three hundred twenty thousand, two hundred twenty".