2181906432 has 90 divisors (see below), whose sum is σ = 6303518858. Its totient is φ = 727252992.

The previous prime is 2181906413. The next prime is 2181906481. The reversal of 2181906432 is 2346091812.

2181906432 is a `hidden beast` number, since 2 + 1 + 8 + 1 + 9 + 0 + 643 + 2 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1751924736 + 429981696 = 41856^2 + 20736^2 .

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 polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 140058 + ... + 154854.

Almost surely, 2^2181906432 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2181906432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3151759429).

2181906432 is an abundant number, since it is smaller than the sum of its proper divisors (4121612426).

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

2181906432 is an equidigital number, since it uses as much as digits as its factorization.

2181906432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14831 (or 14802 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 2181906432 is about 46710.8813018980. The cubic root of 2181906432 is about 1297.0161212605.

The spelling of 2181906432 in words is "two billion, one hundred eighty-one million, nine hundred six thousand, four hundred thirty-two".