6396481921 has 4 divisors (see below), whose sum is σ = 6396891732. Its totient is φ = 6396072112.

The previous prime is 6396481891. The next prime is 6396481939. The reversal of 6396481921 is 1291846936.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5603271025 + 793210896 = 74855^2 + 28164^2 .

It is a cyclic number.

It is not a de Polignac number, because 6396481921 - 2¹⁵ = 6396449153 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6396481981) 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, 180526 + ... + 213031.

It is an arithmetic number, because the mean of its divisors is an integer number (1599222933).

Almost surely, 2^6396481921 is an apocalyptic number.

It is an amenable number.

6396481921 is a deficient number, since it is larger than the sum of its proper divisors (409811).

6396481921 is a wasteful number, since it uses less digits than its factorization.

6396481921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 409810.

The product of its digits is 559872, while the sum is 49.

The square root of 6396481921 is about 79978.0089837200. The cubic root of 6396481921 is about 1856.2952736697.

The spelling of 6396481921 in words is "six billion, three hundred ninety-six million, four hundred eighty-one thousand, nine hundred twenty-one".