19809138 has 16 divisors (see below), whose sum is σ = 39821760. Its totient is φ = 6569136.

The previous prime is 19809133. The next prime is 19809149. The reversal of 19809138 is 83190891.

It is a happy number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 19809096 and 19809105.

It is not an unprimeable number, because it can be changed into a prime (19809133) 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, 7198 + ... + 9561.

It is an arithmetic number, because the mean of its divisors is an integer number (2488860).

Almost surely, 2^19809138 is an apocalyptic number.

19809138 is an abundant number, since it is smaller than the sum of its proper divisors (20012622).

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

19809138 is a wasteful number, since it uses less digits than its factorization.

19809138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16961.

The product of its (nonzero) digits is 15552, while the sum is 39.

The square root of 19809138 is about 4450.7457802036. The cubic root of 19809138 is about 270.5755350001.

The spelling of 19809138 in words is "nineteen million, eight hundred nine thousand, one hundred thirty-eight".