2155643280 has 720 divisors, whose sum is σ = 9138415104. Its totient is φ = 470292480.

The previous prime is 2155643267. The next prime is 2155643317. The reversal of 2155643280 is 823465512.

2155643280 is a `hidden beast` number, since 2 + 1 + 5 + 5 + 643 + 2 + 8 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (720).

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 143 ways as a sum of consecutive naturals, for example, 29529324 + ... + 29529396.

Almost surely, 2^2155643280 is an apocalyptic number.

2155643280 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 2155643280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4569207552).

2155643280 is an abundant number, since it is smaller than the sum of its proper divisors (6982771824).

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

2155643280 is a wasteful number, since it uses less digits than its factorization.

2155643280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 146 (or 121 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 36.

The square root of 2155643280 is about 46428.9056515443. The cubic root of 2155643280 is about 1291.7911300853.

The spelling of 2155643280 in words is "two billion, one hundred fifty-five million, six hundred forty-three thousand, two hundred eighty".