6621399894 has 16 divisors (see below), whose sum is σ = 13366565568. Its totient is φ = 2186505672.

The previous prime is 6621399859. The next prime is 6621399923. The reversal of 6621399894 is 4989931266.

It is a happy number.

It is a super-2 number, since 2×6621399894² = 87685873112526422472, which contains 22 as substring.

It is a congruent number.

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, 5156212 + ... + 5157495.

It is an arithmetic number, because the mean of its divisors is an integer number (835410348).

Almost surely, 2^6621399894 is an apocalyptic number.

6621399894 is an abundant number, since it is smaller than the sum of its proper divisors (6745165674).

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

6621399894 is a wasteful number, since it uses less digits than its factorization.

6621399894 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10313819.

The product of its digits is 5038848, while the sum is 57.

The square root of 6621399894 is about 81371.9846998953. The cubic root of 6621399894 is about 1877.8026135345.

The spelling of 6621399894 in words is "six billion, six hundred twenty-one million, three hundred ninety-nine thousand, eight hundred ninety-four".