18196421 has 2 divisors, whose sum is σ = 18196422. Its totient is φ = 18196420.

The previous prime is 18196417. The next prime is 18196441. The reversal of 18196421 is 12469181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9523396 + 8673025 = 3086^2 + 2945^2 .

It is an emirp because it is prime and its reverse (12469181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18196421 - 2² = 18196417 is a prime.

It is a super-2 number, since 2×18196421² = 662219474418482, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18196441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9098210 + 9098211.

It is an arithmetic number, because the mean of its divisors is an integer number (9098211).

Almost surely, 2^18196421 is an apocalyptic number.

It is an amenable number.

18196421 is a deficient number, since it is larger than the sum of its proper divisors (1).

18196421 is an equidigital number, since it uses as much as digits as its factorization.

18196421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3456, while the sum is 32.

The square root of 18196421 is about 4265.7263156466. The cubic root of 18196421 is about 263.0239680913.

The spelling of 18196421 in words is "eighteen million, one hundred ninety-six thousand, four hundred twenty-one".