2171748781 has 24 divisors (see below), whose sum is σ = 2344927104. Its totient is φ = 2009407680.

The previous prime is 2171748769. The next prime is 2171748833. The reversal of 2171748781 is 1878471712.

It is not a de Polignac number, because 2171748781 - 2⁹ = 2171748269 is a prime.

It is a super-2 number, since 2×2171748781² = 9432985535549971922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2171748731) by changing a digit.

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, 2208816 + ... + 2209798.

It is an arithmetic number, because the mean of its divisors is an integer number (97705296).

Almost surely, 2^2171748781 is an apocalyptic number.

It is an amenable number.

2171748781 is a deficient number, since it is larger than the sum of its proper divisors (173178323).

2171748781 is an equidigital number, since it uses as much as digits as its factorization.

2171748781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1149 (or 1120 counting only the distinct ones).

The product of its digits is 175616, while the sum is 46.

The square root of 2171748781 is about 46602.0255031903. The cubic root of 2171748781 is about 1295.0002794631. Note that the first 3 decimals are identical.

The spelling of 2171748781 in words is "two billion, one hundred seventy-one million, seven hundred forty-eight thousand, seven hundred eighty-one".