19121818 has 4 divisors (see below), whose sum is σ = 28682730. Its totient is φ = 9560908.

The previous prime is 19121803. The next prime is 19121827. The reversal of 19121818 is 81812191.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81812191 = 953 ⋅85847.

It can be written as a sum of positive squares in only one way, i.e., 12552849 + 6568969 = 3543^2 + 2563^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 19121818.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4780453 + ... + 4780456.

Almost surely, 2^19121818 is an apocalyptic number.

19121818 is a deficient number, since it is larger than the sum of its proper divisors (9560912).

19121818 is an equidigital number, since it uses as much as digits as its factorization.

19121818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9560911.

The product of its digits is 1152, while the sum is 31.

The square root of 19121818 is about 4372.8501003350. The cubic root of 19121818 is about 267.4092299824.

The spelling of 19121818 in words is "nineteen million, one hundred twenty-one thousand, eight hundred eighteen".