2182985721 has 30 divisors (see below), whose sum is σ = 3793418970. Its totient is φ = 1247418144.

The previous prime is 2182985699. The next prime is 2182985741. The reversal of 2182985721 is 1275892812.

It can be written as a sum of positive squares in only one way, i.e., 1414587321 + 768398400 = 37611^2 + 27720^2 .

It is not a de Polignac number, because 2182985721 - 2⁹ = 2182985209 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2182985741) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 271036 + ... + 278973.

It is an arithmetic number, because the mean of its divisors is an integer number (126447299).

Almost surely, 2^2182985721 is an apocalyptic number.

2182985721 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2182985721 is a deficient number, since it is larger than the sum of its proper divisors (1610433249).

2182985721 is an equidigital number, since it uses as much as digits as its factorization.

2182985721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 550035 (or 550019 counting only the distinct ones).

The product of its digits is 161280, while the sum is 45.

The square root of 2182985721 is about 46722.4327384609. The cubic root of 2182985721 is about 1297.2299441298.

The spelling of 2182985721 in words is "two billion, one hundred eighty-two million, nine hundred eighty-five thousand, seven hundred twenty-one".