19720000138 has 4 divisors (see below), whose sum is σ = 29580000210. Its totient is φ = 9860000068.

The previous prime is 19720000123. The next prime is 19720000163. The reversal of 19720000138 is 83100002791.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 83100002791 = 13 ⋅6392307907.

It can be written as a sum of positive squares in only one way, i.e., 16943447889 + 2776552249 = 130167^2 + 52693^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4930000033 + ... + 4930000036.

Almost surely, 2^19720000138 is an apocalyptic number.

19720000138 is a deficient number, since it is larger than the sum of its proper divisors (9860000072).

19720000138 is an equidigital number, since it uses as much as digits as its factorization.

19720000138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9860000071.

The product of its (nonzero) digits is 3024, while the sum is 31.

The spelling of 19720000138 in words is "nineteen billion, seven hundred twenty million, one hundred thirty-eight", and thus it is an aban number.