18484721 has 2 divisors, whose sum is σ = 18484722. Its totient is φ = 18484720.

The previous prime is 18484679. The next prime is 18484733. The reversal of 18484721 is 12748481.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13359025 + 5125696 = 3655^2 + 2264^2 .

It is an emirp because it is prime and its reverse (12748481) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18484721 - 2¹⁴ = 18468337 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18484751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9242360 + 9242361.

It is an arithmetic number, because the mean of its divisors is an integer number (9242361).

Almost surely, 2^18484721 is an apocalyptic number.

It is an amenable number.

18484721 is a deficient number, since it is larger than the sum of its proper divisors (1).

18484721 is an equidigital number, since it uses as much as digits as its factorization.

18484721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14336, while the sum is 35.

The square root of 18484721 is about 4299.3861189709. The cubic root of 18484721 is about 264.4057933308.

The spelling of 18484721 in words is "eighteen million, four hundred eighty-four thousand, seven hundred twenty-one".