6426656640 has 320 divisors, whose sum is σ = 23130882720. Its totient is φ = 1700352000.

The previous prime is 6426656617. The next prime is 6426656641. The reversal of 6426656640 is 466566246.

6426656640 is a `hidden beast` number, since 6 + 42 + 6 + 6 + 566 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (320).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6426656641) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 7827430 + ... + 7828250.

Almost surely, 2^6426656640 is an apocalyptic number.

6426656640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6426656640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (11565441360).

6426656640 is an abundant number, since it is smaller than the sum of its proper divisors (16704226080).

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

6426656640 is a wasteful number, since it uses less digits than its factorization.

6426656640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1003 (or 982 counting only the distinct ones).

The product of its (nonzero) digits is 1244160, while the sum is 45.

The square root of 6426656640 is about 80166.4308797641. The cubic root of 6426656640 is about 1859.2096538100.

The spelling of 6426656640 in words is "six billion, four hundred twenty-six million, six hundred fifty-six thousand, six hundred forty".