18421633 has 2 divisors, whose sum is σ = 18421634. Its totient is φ = 18421632.

The previous prime is 18421631. The next prime is 18421639. The reversal of 18421633 is 33612481.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18378369 + 43264 = 4287^2 + 208^2 .

It is a cyclic number.

It is not a de Polignac number, because 18421633 - 2¹ = 18421631 is a prime.

Together with 18421631, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18421631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9210816 + 9210817.

It is an arithmetic number, because the mean of its divisors is an integer number (9210817).

Almost surely, 2^18421633 is an apocalyptic number.

It is an amenable number.

18421633 is a deficient number, since it is larger than the sum of its proper divisors (1).

18421633 is an equidigital number, since it uses as much as digits as its factorization.

18421633 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3456, while the sum is 28.

The square root of 18421633 is about 4292.0429867372. The cubic root of 18421633 is about 264.1046464921.

The spelling of 18421633 in words is "eighteen million, four hundred twenty-one thousand, six hundred thirty-three".