2100265721 has 2 divisors, whose sum is σ = 2100265722. Its totient is φ = 2100265720.

The previous prime is 2100265709. The next prime is 2100265729. The reversal of 2100265721 is 1275620012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1424005696 + 676260025 = 37736^2 + 26005^2 .

It is a cyclic number.

It is not a de Polignac number, because 2100265721 - 2¹⁰ = 2100264697 is a prime.

It is a super-2 number, since 2×2100265721² = 8822232197615299682, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (2100265729) 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 as a sum of consecutive naturals, namely, 1050132860 + 1050132861.

It is an arithmetic number, because the mean of its divisors is an integer number (1050132861).

Almost surely, 2^2100265721 is an apocalyptic number.

It is an amenable number.

2100265721 is a deficient number, since it is larger than the sum of its proper divisors (1).

2100265721 is an equidigital number, since it uses as much as digits as its factorization.

2100265721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 2100265721 is about 45828.6561116514. The cubic root of 2100265721 is about 1280.6331748962.

Adding to 2100265721 its reverse (1275620012), we get a palindrome (3375885733).

The spelling of 2100265721 in words is "two billion, one hundred million, two hundred sixty-five thousand, seven hundred twenty-one".