6478656821 has 32 divisors (see below), whose sum is σ = 8201652480. Its totient is φ = 4979874816.

The previous prime is 6478656797. The next prime is 6478656827. The reversal of 6478656821 is 1286568746.

It is a happy number.

It is not a de Polignac number, because 6478656821 - 2²² = 6474462517 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6478656827) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3396350 + ... + 3398256.

It is an arithmetic number, because the mean of its divisors is an integer number (256301640).

Almost surely, 2^6478656821 is an apocalyptic number.

It is an amenable number.

6478656821 is a deficient number, since it is larger than the sum of its proper divisors (1722995659).

6478656821 is a wasteful number, since it uses less digits than its factorization.

6478656821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2973.

The product of its digits is 3870720, while the sum is 53.

The square root of 6478656821 is about 80490.1038699789. The cubic root of 6478656821 is about 1864.2106807992.

The spelling of 6478656821 in words is "six billion, four hundred seventy-eight million, six hundred fifty-six thousand, eight hundred twenty-one".