6420209 has 4 divisors (see below), whose sum is σ = 6479220. Its totient is φ = 6361200.

The previous prime is 6420199. The next prime is 6420221. The reversal of 6420209 is 9020246.

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 2093809 + 4326400 = 1447^2 + 2080^2 .

It is a cyclic number.

It is not a de Polignac number, because 6420209 - 2⁸ = 6419953 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6420259) 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, 29342 + ... + 29559.

It is an arithmetic number, because the mean of its divisors is an integer number (1619805).

Almost surely, 2^6420209 is an apocalyptic number.

It is an amenable number.

6420209 is a deficient number, since it is larger than the sum of its proper divisors (59011).

6420209 is a wasteful number, since it uses less digits than its factorization.

6420209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59010.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 6420209 is about 2533.8131343886. The cubic root of 6420209 is about 185.8587685741.

The spelling of 6420209 in words is "six million, four hundred twenty thousand, two hundred nine".