18435821 has 2 divisors, whose sum is σ = 18435822. Its totient is φ = 18435820.

The previous prime is 18435817. The next prime is 18435827. The reversal of 18435821 is 12853481.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18062500 + 373321 = 4250^2 + 611^2 .

It is a cyclic number.

It is not a de Polignac number, because 18435821 - 2² = 18435817 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18435827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9217910 + 9217911.

It is an arithmetic number, because the mean of its divisors is an integer number (9217911).

Almost surely, 2^18435821 is an apocalyptic number.

It is an amenable number.

18435821 is a deficient number, since it is larger than the sum of its proper divisors (1).

18435821 is an equidigital number, since it uses as much as digits as its factorization.

18435821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7680, while the sum is 32.

The square root of 18435821 is about 4293.6954945594. The cubic root of 18435821 is about 264.1724319259.

The spelling of 18435821 in words is "eighteen million, four hundred thirty-five thousand, eight hundred twenty-one".