6400321640 has 16 divisors (see below), whose sum is σ = 14400723780. Its totient is φ = 2560128640.

The previous prime is 6400321637. The next prime is 6400321643. The reversal of 6400321640 is 461230046.

It is an interprime number because it is at equal distance from previous prime (6400321637) and next prime (6400321643).

It can be written as a sum of positive squares in 2 ways, for example, as 5931772324 + 468549316 = 77018^2 + 21646^2 .

It is not an unprimeable number, because it can be changed into a prime (6400321643) 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, 80003981 + ... + 80004060.

Almost surely, 2^6400321640 is an apocalyptic number.

It is an amenable number.

6400321640 is an abundant number, since it is smaller than the sum of its proper divisors (8000402140).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6400321640 is a wasteful number, since it uses less digits than its factorization.

6400321640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160008052 (or 160008048 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 26.

The square root of 6400321640 is about 80002.0102247437. The cubic root of 6400321640 is about 1856.6666354373. Note that the first 4 decimals are identical.

Adding to 6400321640 its reverse (461230046), we get a palindrome (6861551686).

The spelling of 6400321640 in words is "six billion, four hundred million, three hundred twenty-one thousand, six hundred forty".