2005001721 has 64 divisors (see below), whose sum is σ = 3161706240. Its totient is φ = 1254113280.

The previous prime is 2005001693. The next prime is 2005001749. The reversal of 2005001721 is 1271005002.

It is an interprime number because it is at equal distance from previous prime (2005001693) and next prime (2005001749).

It is not a de Polignac number, because 2005001721 - 2⁵ = 2005001689 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 2005001694 and 2005001703.

It is not an unprimeable number, because it can be changed into a prime (2005001821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3474585 + ... + 3475161.

It is an arithmetic number, because the mean of its divisors is an integer number (49401660).

Almost surely, 2^2005001721 is an apocalyptic number.

It is an amenable number.

2005001721 is a deficient number, since it is larger than the sum of its proper divisors (1156704519).

2005001721 is a wasteful number, since it uses less digits than its factorization.

2005001721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 743 (or 737 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 2005001721 is about 44777.2455718303. The cubic root of 2005001721 is about 1260.9704711573.

Adding to 2005001721 its reverse (1271005002), we get a palindrome (3276006723).

The spelling of 2005001721 in words is "two billion, five million, one thousand, seven hundred twenty-one".