19121801938 has 4 divisors (see below), whose sum is σ = 28682702910. Its totient is φ = 9560900968.

The previous prime is 19121801917. The next prime is 19121801953. The reversal of 19121801938 is 83910812191.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 18243094489 + 878707449 = 135067^2 + 29643^2 .

It is a super-2 number, since 2×19121801938² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 19121801894 and 19121801903.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4780450483 + ... + 4780450486.

Almost surely, 2^19121801938 is an apocalyptic number.

19121801938 is a deficient number, since it is larger than the sum of its proper divisors (9560900972).

19121801938 is an equidigital number, since it uses as much as digits as its factorization.

19121801938 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9560900971.

The product of its (nonzero) digits is 31104, while the sum is 43.

The spelling of 19121801938 in words is "nineteen billion, one hundred twenty-one million, eight hundred one thousand, nine hundred thirty-eight".