18442421 has 2 divisors, whose sum is σ = 18442422. Its totient is φ = 18442420.

The previous prime is 18442409. The next prime is 18442441. The reversal of 18442421 is 12424481.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16443025 + 1999396 = 4055^2 + 1414^2 .

It is an emirp because it is prime and its reverse (12424481) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18442421 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18442441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9221210 + 9221211.

It is an arithmetic number, because the mean of its divisors is an integer number (9221211).

Almost surely, 2^18442421 is an apocalyptic number.

It is an amenable number.

18442421 is a deficient number, since it is larger than the sum of its proper divisors (1).

18442421 is an equidigital number, since it uses as much as digits as its factorization.

18442421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2048, while the sum is 26.

The square root of 18442421 is about 4294.4639944934. The cubic root of 18442421 is about 264.2039526274.

The spelling of 18442421 in words is "eighteen million, four hundred forty-two thousand, four hundred twenty-one".