6436891648 has 88 divisors (see below), whose sum is σ = 14074582464. Its totient is φ = 2918092800.

The previous prime is 6436891631. The next prime is 6436891667. The reversal of 6436891648 is 8461986346.

It is a tau number, because it is divible by the number of its divisors (88).

It is a Smith number, since the sum of its digits (55) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7783011 + ... + 7783837.

Almost surely, 2^6436891648 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6436891648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (7037291232).

6436891648 is an abundant number, since it is smaller than the sum of its proper divisors (7637690816).

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

6436891648 is a wasteful number, since it uses less digits than its factorization.

6436891648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1549 (or 1531 counting only the distinct ones).

The product of its digits is 5971968, while the sum is 55.

The square root of 6436891648 is about 80230.2414803795. The cubic root of 6436891648 is about 1860.1961145200.

The spelling of 6436891648 in words is "six billion, four hundred thirty-six million, eight hundred ninety-one thousand, six hundred forty-eight".