18409987 has 2 divisors, whose sum is σ = 18409988. Its totient is φ = 18409986.

The previous prime is 18409969. The next prime is 18410003. The reversal of 18409987 is 78990481.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18409987 is a prime.

It is not a weakly prime, because it can be changed into another prime (18409907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9204993 + 9204994.

It is an arithmetic number, because the mean of its divisors is an integer number (9204994).

Almost surely, 2^18409987 is an apocalyptic number.

18409987 is a deficient number, since it is larger than the sum of its proper divisors (1).

18409987 is an equidigital number, since it uses as much as digits as its factorization.

18409987 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 145152, while the sum is 46.

The square root of 18409987 is about 4290.6860756760. The cubic root of 18409987 is about 264.0489798547.

The spelling of 18409987 in words is "eighteen million, four hundred nine thousand, nine hundred eighty-seven".