18813947 has 2 divisors, whose sum is σ = 18813948. Its totient is φ = 18813946.

The previous prime is 18813943. The next prime is 18813961. The reversal of 18813947 is 74931881.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18813947 - 2² = 18813943 is a prime.

It is not a weakly prime, because it can be changed into another prime (18813941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9406973 + 9406974.

It is an arithmetic number, because the mean of its divisors is an integer number (9406974).

Almost surely, 2^18813947 is an apocalyptic number.

18813947 is a deficient number, since it is larger than the sum of its proper divisors (1).

18813947 is an equidigital number, since it uses as much as digits as its factorization.

18813947 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48384, while the sum is 41.

The square root of 18813947 is about 4337.5046974038. The cubic root of 18813947 is about 265.9663166123.

The spelling of 18813947 in words is "eighteen million, eight hundred thirteen thousand, nine hundred forty-seven".