1997818 has 4 divisors (see below), whose sum is σ = 2996730. Its totient is φ = 998908.

The previous prime is 1997813. The next prime is 1997833. The reversal of 1997818 is 8187991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8187991 = 7 ⋅1169713.

It can be written as a sum of positive squares in only one way, i.e., 1138489 + 859329 = 1067^2 + 927^2 .

It is a super-2 number, since 2×1997818² = 7982553522248, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1997813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499453 + ... + 499456.

2^1997818 is an apocalyptic number.

1997818 is a deficient number, since it is larger than the sum of its proper divisors (998912).

1997818 is an equidigital number, since it uses as much as digits as its factorization.

1997818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 998911.

The product of its digits is 36288, while the sum is 43.

The square root of 1997818 is about 1413.4418983460. The cubic root of 1997818 is about 125.9462691876.

The spelling of 1997818 in words is "one million, nine hundred ninety-seven thousand, eight hundred eighteen".