18863521 has 2 divisors, whose sum is σ = 18863522. Its totient is φ = 18863520.

The previous prime is 18863503. The next prime is 18863527. The reversal of 18863521 is 12536881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16646400 + 2217121 = 4080^2 + 1489^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18863521 is a prime.

It is not a weakly prime, because it can be changed into another prime (18863527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9431760 + 9431761.

It is an arithmetic number, because the mean of its divisors is an integer number (9431761).

Almost surely, 2^18863521 is an apocalyptic number.

It is an amenable number.

18863521 is a deficient number, since it is larger than the sum of its proper divisors (1).

18863521 is an equidigital number, since it uses as much as digits as its factorization.

18863521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11520, while the sum is 34.

The square root of 18863521 is about 4343.2155138791. The cubic root of 18863521 is about 266.1997152790.

The spelling of 18863521 in words is "eighteen million, eight hundred sixty-three thousand, five hundred twenty-one".