18989947 has 2 divisors, whose sum is σ = 18989948. Its totient is φ = 18989946.

The previous prime is 18989939. The next prime is 18989959. The reversal of 18989947 is 74998981.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18989947 - 2³ = 18989939 is a prime.

It is not a weakly prime, because it can be changed into another prime (18980947) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9494973 + 9494974.

It is an arithmetic number, because the mean of its divisors is an integer number (9494974).

Almost surely, 2^18989947 is an apocalyptic number.

18989947 is a deficient number, since it is larger than the sum of its proper divisors (1).

18989947 is an equidigital number, since it uses as much as digits as its factorization.

18989947 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1306368, while the sum is 55.

The square root of 18989947 is about 4357.7456327785. The cubic root of 18989947 is about 266.7930943909.

The spelling of 18989947 in words is "eighteen million, nine hundred eighty-nine thousand, nine hundred forty-seven".