5165121721 has 4 divisors (see below), whose sum is σ = 5165273232. Its totient is φ = 5164970212.

The previous prime is 5165121677. The next prime is 5165121727. The reversal of 5165121721 is 1271215615.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 5165121721 - 2⁷ = 5165121593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (5165121727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1950 + ... + 101656.

It is an arithmetic number, because the mean of its divisors is an integer number (1291318308).

Almost surely, 2^5165121721 is an apocalyptic number.

It is an amenable number.

5165121721 is a deficient number, since it is larger than the sum of its proper divisors (151511).

5165121721 is an equidigital number, since it uses as much as digits as its factorization.

5165121721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151510.

The product of its digits is 4200, while the sum is 31.

The square root of 5165121721 is about 71868.7812683644. The cubic root of 5165121721 is about 1728.5960655899.

The spelling of 5165121721 in words is "five billion, one hundred sixty-five million, one hundred twenty-one thousand, seven hundred twenty-one".