6401721 has 8 divisors (see below), whose sum is σ = 8830080. Its totient is φ = 4120592.

The previous prime is 6401719. The next prime is 6401723. The reversal of 6401721 is 1271046.

It is an interprime number because it is at equal distance from previous prime (6401719) and next prime (6401723).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6401721 - 2¹ = 6401719 is a prime.

It is a super-3 number, since 3×6401721³ (a number of 21 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (6401723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36705 + ... + 36878.

It is an arithmetic number, because the mean of its divisors is an integer number (1103760).

Almost surely, 2^6401721 is an apocalyptic number.

It is an amenable number.

6401721 is a deficient number, since it is larger than the sum of its proper divisors (2428359).

6401721 is a wasteful number, since it uses less digits than its factorization.

6401721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73615.

The product of its (nonzero) digits is 336, while the sum is 21.

The square root of 6401721 is about 2530.1622477620. The cubic root of 6401721 is about 185.6801938830.

Adding to 6401721 its reverse (1271046), we get a palindrome (7672767).

The spelling of 6401721 in words is "six million, four hundred one thousand, seven hundred twenty-one".