19866638905 has 8 divisors (see below), whose sum is σ = 24230786184. Its totient is φ = 15632764800.

The previous prime is 19866638881. The next prime is 19866638917. The reversal of 19866638905 is 50983666891.

It can be written as a sum of positive squares in 4 ways, for example, as 1631917609 + 18234721296 = 40397^2 + 135036^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 19866638905 - 2⁵ = 19866638873 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (61).

It is a Duffinian 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, 32567956 + ... + 32568565.

It is an arithmetic number, because the mean of its divisors is an integer number (3028848273).

Almost surely, 2^19866638905 is an apocalyptic number.

It is an amenable number.

19866638905 is a deficient number, since it is larger than the sum of its proper divisors (4364147279).

19866638905 is an equidigital number, since it uses as much as digits as its factorization.

19866638905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65136587.

The product of its (nonzero) digits is 16796160, while the sum is 61.

The spelling of 19866638905 in words is "nineteen billion, eight hundred sixty-six million, six hundred thirty-eight thousand, nine hundred five".