2169151921 has 4 divisors (see below), whose sum is σ = 2169267700. Its totient is φ = 2169036144.

The previous prime is 2169151909. The next prime is 2169151937. The reversal of 2169151921 is 1291519612.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 1180678321 + 988473600 = 34361^2 + 31440^2 .

It is a cyclic number.

It is not a de Polignac number, because 2169151921 - 2⁷ = 2169151793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2169151991) 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, 22626 + ... + 69643.

It is an arithmetic number, because the mean of its divisors is an integer number (542316925).

Almost surely, 2^2169151921 is an apocalyptic number.

It is an amenable number.

2169151921 is a deficient number, since it is larger than the sum of its proper divisors (115779).

2169151921 is an equidigital number, since it uses as much as digits as its factorization.

2169151921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115778.

The product of its digits is 9720, while the sum is 37.

The square root of 2169151921 is about 46574.1550755352. The cubic root of 2169151921 is about 1294.4839097750.

The spelling of 2169151921 in words is "two billion, one hundred sixty-nine million, one hundred fifty-one thousand, nine hundred twenty-one".