18935821 has 2 divisors, whose sum is σ = 18935822. Its totient is φ = 18935820.

The previous prime is 18935789. The next prime is 18935843. The reversal of 18935821 is 12853981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18826921 + 108900 = 4339^2 + 330^2 .

It is a cyclic number.

It is not a de Polignac number, because 18935821 - 2⁵ = 18935789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18935881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9467910 + 9467911.

It is an arithmetic number, because the mean of its divisors is an integer number (9467911).

Almost surely, 2^18935821 is an apocalyptic number.

It is an amenable number.

18935821 is a deficient number, since it is larger than the sum of its proper divisors (1).

18935821 is an equidigital number, since it uses as much as digits as its factorization.

18935821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17280, while the sum is 37.

The square root of 18935821 is about 4351.5308800467. The cubic root of 18935821 is about 266.5393779659.

The spelling of 18935821 in words is "eighteen million, nine hundred thirty-five thousand, eight hundred twenty-one".