2193891921 has 27 divisors (see below), whose sum is σ = 3434331537. Its totient is φ = 1348963200.

The previous prime is 2193891913. The next prime is 2193891937. The reversal of 2193891921 is 1291983912.

The square root of 2193891921 is 46839.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 1803276225 + 390615696 = 42465^2 + 19764^2 .

It is not a de Polignac number, because 2193891921 - 2³ = 2193891913 is a prime.

It is a super-2 number, since 2×2193891921² = 9626323522058140482, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2193891121) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 1826121 + ... + 1827321.

Almost surely, 2^2193891921 is an apocalyptic number.

2193891921 is the 46839-th square number.

2193891921 is the 23420-th centered octagonal number.

It is an amenable number.

2193891921 is a deficient number, since it is larger than the sum of its proper divisors (1240439616).

2193891921 is an equidigital number, since it uses as much as digits as its factorization.

2193891921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2434 (or 1217 counting only the distinct ones).

The product of its digits is 69984, while the sum is 45.

The cubic root of 2193891921 is about 1299.3866773547.

The spelling of 2193891921 in words is "two billion, one hundred ninety-three million, eight hundred ninety-one thousand, nine hundred twenty-one".