6428267721 has 6 divisors (see below), whose sum is σ = 9285275610. Its totient is φ = 4285511808.

The previous prime is 6428267717. The next prime is 6428267737. The reversal of 6428267721 is 1277628246.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 5652032400 + 776235321 = 75180^2 + 27861^2 .

It is not a de Polignac number, because 6428267721 - 2² = 6428267717 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (6428267761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 357125976 + ... + 357125993.

It is an arithmetic number, because the mean of its divisors is an integer number (1547545935).

Almost surely, 2^6428267721 is an apocalyptic number.

It is an amenable number.

6428267721 is a deficient number, since it is larger than the sum of its proper divisors (2857007889).

6428267721 is a wasteful number, since it uses less digits than its factorization.

6428267721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 714251975 (or 714251972 counting only the distinct ones).

The product of its digits is 451584, while the sum is 45.

The square root of 6428267721 is about 80176.4786018942. The cubic root of 6428267721 is about 1859.3650008929.

The spelling of 6428267721 in words is "six billion, four hundred twenty-eight million, two hundred sixty-seven thousand, seven hundred twenty-one".