6420139409 has 4 divisors (see below), whose sum is σ = 6476954916. Its totient is φ = 6363323904.

The previous prime is 6420139399. The next prime is 6420139507. The reversal of 6420139409 is 9049310246.

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 59598400 + 6360541009 = 7720^2 + 79753^2 .

It is a cyclic number.

It is not a de Polignac number, because 6420139409 - 2¹⁶ = 6420073873 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (6420139309) 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 3 ways as a sum of consecutive naturals, for example, 28407584 + ... + 28407809.

It is an arithmetic number, because the mean of its divisors is an integer number (1619238729).

Almost surely, 2^6420139409 is an apocalyptic number.

It is an amenable number.

6420139409 is a deficient number, since it is larger than the sum of its proper divisors (56815507).

6420139409 is a wasteful number, since it uses less digits than its factorization.

6420139409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56815506.

The product of its (nonzero) digits is 46656, while the sum is 38.

The square root of 6420139409 is about 80125.7724393344. The cubic root of 6420139409 is about 1858.5809704126.

The spelling of 6420139409 in words is "six billion, four hundred twenty million, one hundred thirty-nine thousand, four hundred nine".