2171261664 has 144 divisors (see below), whose sum is σ = 7254125424. Its totient is φ = 607334400.

The previous prime is 2171261647. The next prime is 2171261671. The reversal of 2171261664 is 4661621712.

2171261664 is a `hidden beast` number, since 21 + 7 + 12 + 616 + 6 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

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

It is a congruent number.

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 23 ways as a sum of consecutive naturals, for example, 14824 + ... + 67544.

It is an arithmetic number, because the mean of its divisors is an integer number (50375871).

Almost surely, 2^2171261664 is an apocalyptic number.

2171261664 is a gapful number since it is divisible by the number (24) 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 2171261664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3627062712).

2171261664 is an abundant number, since it is smaller than the sum of its proper divisors (5082863760).

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

2171261664 is a wasteful number, since it uses less digits than its factorization.

2171261664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52761 (or 52750 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 2171261664 is about 46596.7988600075. The cubic root of 2171261664 is about 1294.9034506116.

The spelling of 2171261664 in words is "two billion, one hundred seventy-one million, two hundred sixty-one thousand, six hundred sixty-four".