18975821 has 2 divisors, whose sum is σ = 18975822. Its totient is φ = 18975820.

The previous prime is 18975811. The next prime is 18975823. The reversal of 18975821 is 12857981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14523721 + 4452100 = 3811^2 + 2110^2 .

It is a cyclic number.

It is not a de Polignac number, because 18975821 - 2¹⁰ = 18974797 is a prime.

Together with 18975823, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18975823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9487910 + 9487911.

It is an arithmetic number, because the mean of its divisors is an integer number (9487911).

Almost surely, 2^18975821 is an apocalyptic number.

It is an amenable number.

18975821 is a deficient number, since it is larger than the sum of its proper divisors (1).

18975821 is an equidigital number, since it uses as much as digits as its factorization.

18975821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40320, while the sum is 41.

The square root of 18975821 is about 4356.1245390829. The cubic root of 18975821 is about 266.7269250977.

The spelling of 18975821 in words is "eighteen million, nine hundred seventy-five thousand, eight hundred twenty-one".