18550921 has 2 divisors, whose sum is σ = 18550922. Its totient is φ = 18550920.

The previous prime is 18550907. The next prime is 18550937. The reversal of 18550921 is 12905581.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9765625 + 8785296 = 3125^2 + 2964^2 .

It is a cyclic number.

It is not a de Polignac number, because 18550921 - 2⁷ = 18550793 is a prime.

It is equal to p_1184197 and since 18550921 and 1184197 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (18550321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9275460 + 9275461.

It is an arithmetic number, because the mean of its divisors is an integer number (9275461).

Almost surely, 2^18550921 is an apocalyptic number.

It is an amenable number.

18550921 is a deficient number, since it is larger than the sum of its proper divisors (1).

18550921 is an equidigital number, since it uses as much as digits as its factorization.

18550921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3600, while the sum is 31.

The square root of 18550921 is about 4307.0780118312. The cubic root of 18550921 is about 264.7210592828.

The spelling of 18550921 in words is "eighteen million, five hundred fifty thousand, nine hundred twenty-one".