2100724985 has 4 divisors (see below), whose sum is σ = 2520869988. Its totient is φ = 1680579984.

The previous prime is 2100724981. The next prime is 2100724999. The reversal of 2100724985 is 5894270012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1506681856 + 594043129 = 38816^2 + 24373^2 .

It is a cyclic number.

It is not a de Polignac number, because 2100724985 - 2² = 2100724981 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2100724981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 210072494 + ... + 210072503.

It is an arithmetic number, because the mean of its divisors is an integer number (630217497).

Almost surely, 2^2100724985 is an apocalyptic number.

It is an amenable number.

2100724985 is a deficient number, since it is larger than the sum of its proper divisors (420145003).

2100724985 is an equidigital number, since it uses as much as digits as its factorization.

2100724985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 420145002.

The product of its (nonzero) digits is 40320, while the sum is 38.

The square root of 2100724985 is about 45833.6665018194. Note that the first 3 decimals coincide. The cubic root of 2100724985 is about 1280.7265132206.

Adding to 2100724985 its reverse (5894270012), we get a palindrome (7994994997).

The spelling of 2100724985 in words is "two billion, one hundred million, seven hundred twenty-four thousand, nine hundred eighty-five".