6401808721 has 8 divisors (see below), whose sum is σ = 7981475904. Its totient is φ = 4988422320.

The previous prime is 6401808703. The next prime is 6401808767. The reversal of 6401808721 is 1278081046.

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

It is not a de Polignac number, because 6401808721 - 2⁵ = 6401808689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6401808701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41570110 + ... + 41570263.

It is an arithmetic number, because the mean of its divisors is an integer number (997684488).

Almost surely, 2^6401808721 is an apocalyptic number.

It is an amenable number.

6401808721 is a deficient number, since it is larger than the sum of its proper divisors (1579667183).

6401808721 is a wasteful number, since it uses less digits than its factorization.

6401808721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83140391.

The product of its (nonzero) digits is 21504, while the sum is 37.

The square root of 6401808721 is about 80011.3037076637. The cubic root of 6401808721 is about 1856.8104198710.

Adding to 6401808721 its reverse (1278081046), we get a palindrome (7679889767).

The spelling of 6401808721 in words is "six billion, four hundred one million, eight hundred eight thousand, seven hundred twenty-one".