18821897 has 2 divisors, whose sum is σ = 18821898. Its totient is φ = 18821896.

The previous prime is 18821893. The next prime is 18821903. The reversal of 18821897 is 79812881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15649936 + 3171961 = 3956^2 + 1781^2 .

It is an emirp because it is prime and its reverse (79812881) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18821897 - 2² = 18821893 is a prime.

It is not a weakly prime, because it can be changed into another prime (18821893) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9410948 + 9410949.

It is an arithmetic number, because the mean of its divisors is an integer number (9410949).

Almost surely, 2^18821897 is an apocalyptic number.

It is an amenable number.

18821897 is a deficient number, since it is larger than the sum of its proper divisors (1).

18821897 is an equidigital number, since it uses as much as digits as its factorization.

18821897 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64512, while the sum is 44.

The square root of 18821897 is about 4338.4210261338. The cubic root of 18821897 is about 266.0037734780.

The spelling of 18821897 in words is "eighteen million, eight hundred twenty-one thousand, eight hundred ninety-seven".