6406381 has 2 divisors, whose sum is σ = 6406382. Its totient is φ = 6406380.

The previous prime is 6406369. The next prime is 6406427. The reversal of 6406381 is 1836046.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4583881 + 1822500 = 2141^2 + 1350^2 .

It is a cyclic number.

It is not a de Polignac number, because 6406381 - 2¹⁵ = 6373613 is a prime.

It is a super-2 number, since 2×6406381² = 82083435034322, which contains 22 as substring.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6406321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3203190 + 3203191.

It is an arithmetic number, because the mean of its divisors is an integer number (3203191).

Almost surely, 2^6406381 is an apocalyptic number.

It is an amenable number.

6406381 is a deficient number, since it is larger than the sum of its proper divisors (1).

6406381 is an equidigital number, since it uses as much as digits as its factorization.

6406381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 6406381 is about 2531.0829697977. The cubic root of 6406381 is about 185.7252369704.

It can be divided in two parts, 640 and 6381, that added together give a triangular number (7021 = T₁₁₈).

The spelling of 6406381 in words is "six million, four hundred six thousand, three hundred eighty-one".