2161578920 has 32 divisors (see below), whose sum is σ = 4943288520. Its totient is φ = 850456320.

The previous prime is 2161578899. The next prime is 2161578959. The reversal of 2161578920 is 298751612.

It can be written as a sum of positive squares in 4 ways, for example, as 365344996 + 1796233924 = 19114^2 + 42382^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 440507 + ... + 445386.

Almost surely, 2^2161578920 is an apocalyptic number.

2161578920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2161578920 is an abundant number, since it is smaller than the sum of its proper divisors (2781709600).

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

2161578920 is a wasteful number, since it uses less digits than its factorization.

2161578920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 885965 (or 885961 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 41.

The square root of 2161578920 is about 46492.7835260484. The cubic root of 2161578920 is about 1292.9757076767.

The spelling of 2161578920 in words is "two billion, one hundred sixty-one million, five hundred seventy-eight thousand, nine hundred twenty".