6406421 has 4 divisors (see below), whose sum is σ = 7321632. Its totient is φ = 5491212.

The previous prime is 6406381. The next prime is 6406427. The reversal of 6406421 is 1246046.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1246046 = 2 ⋅623023.

It is a cyclic number.

It is not a de Polignac number, because 6406421 - 2¹⁰ = 6405397 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6406427) 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, 457595 + ... + 457608.

It is an arithmetic number, because the mean of its divisors is an integer number (1830408).

Almost surely, 2^6406421 is an apocalyptic number.

It is an amenable number.

6406421 is a deficient number, since it is larger than the sum of its proper divisors (915211).

6406421 is an equidigital number, since it uses as much as digits as its factorization.

6406421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 915210.

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 6406421 is about 2531.0908715414. The cubic root of 6406421 is about 185.7256235118.

The spelling of 6406421 in words is "six million, four hundred six thousand, four hundred twenty-one".