6461987840 has 352 divisors, whose sum is σ = 19893302784. Its totient is φ = 1955266560.

The previous prime is 6461987821. The next prime is 6461987879. The reversal of 6461987840 is 487891646.

It is a tau number, because it is divible by the number of its divisors (352).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 14586659 + ... + 14587101.

Almost surely, 2^6461987840 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 6461987840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (9946651392).

6461987840 is an abundant number, since it is smaller than the sum of its proper divisors (13431314944).

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

6461987840 is a wasteful number, since it uses less digits than its factorization.

6461987840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 523 (or 505 counting only the distinct ones).

The product of its (nonzero) digits is 2322432, while the sum is 53.

The square root of 6461987840 is about 80386.4904072817. The cubic root of 6461987840 is about 1862.6104941129.

The spelling of 6461987840 in words is "six billion, four hundred sixty-one million, nine hundred eighty-seven thousand, eight hundred forty".