6440420121 has 4 divisors (see below), whose sum is σ = 8587226832. Its totient is φ = 4293613412.

The previous prime is 6440420099. The next prime is 6440420123. The reversal of 6440420121 is 1210240446.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 6440420121 - 2⁶ = 6440420057 is a prime.

It is a super-2 number, since 2×6440420121² = 82958022669963309282, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 6440420091 and 6440420100.

It is not an unprimeable number, because it can be changed into a prime (6440420123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1073403351 + ... + 1073403356.

It is an arithmetic number, because the mean of its divisors is an integer number (2146806708).

Almost surely, 2^6440420121 is an apocalyptic number.

It is an amenable number.

6440420121 is a deficient number, since it is larger than the sum of its proper divisors (2146806711).

6440420121 is a wasteful number, since it uses less digits than its factorization.

6440420121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2146806710.

The product of its (nonzero) digits is 1536, while the sum is 24.

The square root of 6440420121 is about 80252.2281372922. The cubic root of 6440420121 is about 1860.5359500167.

Adding to 6440420121 its reverse (1210240446), we get a palindrome (7650660567).

The spelling of 6440420121 in words is "six billion, four hundred forty million, four hundred twenty thousand, one hundred twenty-one".