2165721480 has 144 divisors (see below), whose sum is σ = 7621887780. Its totient is φ = 533085696.

The previous prime is 2165721431. The next prime is 2165721497. The reversal of 2165721480 is 841275612.

2165721480 is a `hidden beast` number, since 2 + 1 + 6 + 572 + 1 + 4 + 80 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 21846276 + 2143875204 = 4674^2 + 46302^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 43042 + ... + 78638.

Almost surely, 2^2165721480 is an apocalyptic number.

2165721480 is a gapful number since it is divisible by the number (20) 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 2165721480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3810943890).

2165721480 is an abundant number, since it is smaller than the sum of its proper divisors (5456166300).

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

2165721480 is a wasteful number, since it uses less digits than its factorization.

2165721480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35640 (or 35620 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 36.

The square root of 2165721480 is about 46537.3127715815. The cubic root of 2165721480 is about 1293.8011554372.

The spelling of 2165721480 in words is "two billion, one hundred sixty-five million, seven hundred twenty-one thousand, four hundred eighty".