19966501806 has 16 divisors (see below), whose sum is σ = 39934965504. Its totient is φ = 6655173624.

The previous prime is 19966501801. The next prime is 19966501811. The reversal of 19966501806 is 60810566991.

It is an interprime number because it is at equal distance from previous prime (19966501801) and next prime (19966501811).

It is a super-2 number, since 2×19966501806² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19966501801) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 73131 + ... + 212793.

It is an arithmetic number, because the mean of its divisors is an integer number (2495935344).

Almost surely, 2^19966501806 is an apocalyptic number.

19966501806 is an abundant number, since it is smaller than the sum of its proper divisors (19968463698).

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

19966501806 is a wasteful number, since it uses less digits than its factorization.

19966501806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163495.

The product of its (nonzero) digits is 699840, while the sum is 51.

The spelling of 19966501806 in words is "nineteen billion, nine hundred sixty-six million, five hundred one thousand, eight hundred six".