18821137 has 2 divisors, whose sum is σ = 18821138. Its totient is φ = 18821136.

The previous prime is 18821119. The next prime is 18821141. The reversal of 18821137 is 73112881.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16128256 + 2692881 = 4016^2 + 1641^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18821137 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18821099 and 18821108.

It is not a weakly prime, because it can be changed into another prime (18821147) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9410568 + 9410569.

It is an arithmetic number, because the mean of its divisors is an integer number (9410569).

Almost surely, 2^18821137 is an apocalyptic number.

It is an amenable number.

18821137 is a deficient number, since it is larger than the sum of its proper divisors (1).

18821137 is an equidigital number, since it uses as much as digits as its factorization.

18821137 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2688, while the sum is 31.

The square root of 18821137 is about 4338.3334357792. Note that the first 3 decimals coincide. The cubic root of 18821137 is about 266.0001931519. Note that the first 3 decimals are identical.

The spelling of 18821137 in words is "eighteen million, eight hundred twenty-one thousand, one hundred thirty-seven".