6378706921 has 4 divisors (see below), whose sum is σ = 6380060500. Its totient is φ = 6377353344.

The previous prime is 6378706907. The next prime is 6378706949. The reversal of 6378706921 is 1296078736.

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 3335640025 + 3043066896 = 57755^2 + 55164^2 .

It is a cyclic number.

It is not a de Polignac number, because 6378706921 - 2²³ = 6370318313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6378706951) 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, 669696 + ... + 679153.

It is an arithmetic number, because the mean of its divisors is an integer number (1595015125).

Almost surely, 2^6378706921 is an apocalyptic number.

It is an amenable number.

6378706921 is a deficient number, since it is larger than the sum of its proper divisors (1353579).

6378706921 is a wasteful number, since it uses less digits than its factorization.

6378706921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1353578.

The product of its (nonzero) digits is 762048, while the sum is 49.

The square root of 6378706921 is about 79866.8073795366. The cubic root of 6378706921 is about 1854.5742099286.

The spelling of 6378706921 in words is "six billion, three hundred seventy-eight million, seven hundred six thousand, nine hundred twenty-one".