1565899920 has 360 divisors, whose sum is σ = 6037388136. Its totient is φ = 362299392.

The previous prime is 1565899897. The next prime is 1565899957. The reversal of 1565899920 is 299985651.

1565899920 is a `hidden beast` number, since 1 + 56 + 589 + 9 + 9 + 2 + 0 = 666.

It can be written as a sum of positive squares in 12 ways, for example, as 569108736 + 996791184 = 23856^2 + 31572^2 .

It is a tau number, because it is divible by the number of its divisors (360).

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 2068182 + ... + 2068938.

Almost surely, 2^1565899920 is an apocalyptic number.

1565899920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1565899920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3018694068).

1565899920 is an abundant number, since it is smaller than the sum of its proper divisors (4471488216).

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

1565899920 is a wasteful number, since it uses less digits than its factorization.

1565899920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 819 (or 797 counting only the distinct ones).

The product of its (nonzero) digits is 1749600, while the sum is 54.

The square root of 1565899920 is about 39571.4533470784. The cubic root of 1565899920 is about 1161.2382536451.

The spelling of 1565899920 in words is "one billion, five hundred sixty-five million, eight hundred ninety-nine thousand, nine hundred twenty".