2181965985 has 128 divisors (see below), whose sum is σ = 4251033600. Its totient is φ = 1058158080.

The previous prime is 2181965977. The next prime is 2181965987. The reversal of 2181965985 is 5895691812.

It is not a de Polignac number, because 2181965985 - 2³ = 2181965977 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2181965987) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 8051400 + ... + 8051670.

It is an arithmetic number, because the mean of its divisors is an integer number (33211200).

Almost surely, 2^2181965985 is an apocalyptic number.

It is an amenable number.

2181965985 is a deficient number, since it is larger than the sum of its proper divisors (2069067615).

2181965985 is a wasteful number, since it uses less digits than its factorization.

2181965985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 420 (or 414 counting only the distinct ones).

The product of its digits is 1555200, while the sum is 54.

The square root of 2181965985 is about 46711.5187614361. The cubic root of 2181965985 is about 1297.0279214149.

The spelling of 2181965985 in words is "two billion, one hundred eighty-one million, nine hundred sixty-five thousand, nine hundred eighty-five".