18211643 has 2 divisors, whose sum is σ = 18211644. Its totient is φ = 18211642.

The previous prime is 18211637. The next prime is 18211679. The reversal of 18211643 is 34611281.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18211643 - 2⁶ = 18211579 is a prime.

It is not a weakly prime, because it can be changed into another prime (18211603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9105821 + 9105822.

It is an arithmetic number, because the mean of its divisors is an integer number (9105822).

Almost surely, 2^18211643 is an apocalyptic number.

18211643 is a deficient number, since it is larger than the sum of its proper divisors (1).

18211643 is an equidigital number, since it uses as much as digits as its factorization.

18211643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1152, while the sum is 26.

The square root of 18211643 is about 4267.5101640184. The cubic root of 18211643 is about 263.0972908422.

The spelling of 18211643 in words is "eighteen million, two hundred eleven thousand, six hundred forty-three".