6620781888 has 336 divisors, whose sum is σ = 22883229824. Its totient is φ = 1858775040.

The previous prime is 6620781883. The next prime is 6620781913. The reversal of 6620781888 is 8881870266.

6620781888 is a `hidden beast` number, since 6 + 620 + 7 + 8 + 1 + 8 + 8 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (336).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6620781883) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 6640206 + ... + 6641202.

Almost surely, 2^6620781888 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 6620781888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (11441614912).

6620781888 is an abundant number, since it is smaller than the sum of its proper divisors (16262447936).

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

6620781888 is an equidigital number, since it uses as much as digits as its factorization.

6620781888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1092 (or 1070 counting only the distinct ones).

The product of its (nonzero) digits is 2064384, while the sum is 54.

The square root of 6620781888 is about 81368.1871986835. The cubic root of 6620781888 is about 1877.7441903709.

The spelling of 6620781888 in words is "six billion, six hundred twenty million, seven hundred eighty-one thousand, eight hundred eighty-eight".