6440374019521 has 12 divisors (see below), whose sum is σ = 7340943295920. Its totient is φ = 5632067965680.

The previous prime is 6440374019411. The next prime is 6440374019539. The reversal of 6440374019521 is 1259104730446.

It is not a de Polignac number, because 6440374019521 - 2²⁵ = 6440340465089 is a prime.

It is a super-2 number, since 2×6440374019521² (a number of 26 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (6440374019551) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1002857895 + ... + 1002864316.

It is an arithmetic number, because the mean of its divisors is an integer number (611745274660).

Almost surely, 2^{6440374019521} is an apocalyptic number.

It is an amenable number.

6440374019521 is a deficient number, since it is larger than the sum of its proper divisors (900569276399).

6440374019521 is a wasteful number, since it uses less digits than its factorization.

6440374019521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2005722256 (or 2005722243 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 46.

Adding to 6440374019521 its reverse (1259104730446), we get a palindrome (7699478749967).

The spelling of 6440374019521 in words is "six trillion, four hundred forty billion, three hundred seventy-four million, nineteen thousand, five hundred twenty-one".