2166521280 has 672 divisors, whose sum is σ = 9006474240. Its totient is φ = 436101120.

The previous prime is 2166521257. The next prime is 2166521351. The reversal of 2166521280 is 821256612.

It is a tau number, because it is divible by the number of its divisors (672).

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 27424281 + ... + 27424359.

Almost surely, 2^2166521280 is an apocalyptic number.

2166521280 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 2166521280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4503237120).

2166521280 is an abundant number, since it is smaller than the sum of its proper divisors (6839952960).

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

2166521280 is a wasteful number, since it uses less digits than its factorization.

2166521280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 177 (or 160 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 33.

The square root of 2166521280 is about 46545.9050830468. The cubic root of 2166521280 is about 1293.9604025700.

Adding to 2166521280 its reverse (821256612), we get a palindrome (2987777892).

The spelling of 2166521280 in words is "two billion, one hundred sixty-six million, five hundred twenty-one thousand, two hundred eighty".