6406721764 has 27 divisors (see below), whose sum is σ = 11594080323. Its totient is φ = 3097625400.

The previous prime is 6406721759. The next prime is 6406721767. The reversal of 6406721764 is 4671276046.

The square root of 6406721764 is 80042.

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

It is a super-2 number, since 2×6406721764² = 82092167522622543392, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 6406721764.

It is not an unprimeable number, because it can be changed into a prime (6406721767) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 4961959 + ... + 4963249.

Almost surely, 2^6406721764 is an apocalyptic number.

6406721764 is the 80042-nd square number.

It is an amenable number.

6406721764 is a deficient number, since it is larger than the sum of its proper divisors (5187358559).

6406721764 is an equidigital number, since it uses as much as digits as its factorization.

6406721764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2648 (or 1324 counting only the distinct ones).

The product of its (nonzero) digits is 338688, while the sum is 43.

The cubic root of 6406721764 is about 1857.2852990356.

The spelling of 6406721764 in words is "six billion, four hundred six million, seven hundred twenty-one thousand, seven hundred sixty-four".