6621805890 has 112 divisors (see below), whose sum is σ = 20423815488. Its totient is φ = 1513543968.

The previous prime is 6621805873. The next prime is 6621805909. The reversal of 6621805890 is 985081266.

6621805890 is a `hidden beast` number, since 6 + 62 + 1 + 8 + 0 + 589 + 0 = 666.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

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

It is an unprimeable number.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 13852 + ... + 115911.

Almost surely, 2^6621805890 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6621805890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10211907744).

6621805890 is an abundant number, since it is smaller than the sum of its proper divisors (13802009598).

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

6621805890 is a wasteful number, since it uses less digits than its factorization.

6621805890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129795 (or 129780 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 45.

The square root of 6621805890 is about 81374.4793531731. The cubic root of 6621805890 is about 1877.8409923658.

The spelling of 6621805890 in words is "six billion, six hundred twenty-one million, eight hundred five thousand, eight hundred ninety".