18918457 has 2 divisors, whose sum is σ = 18918458. Its totient is φ = 18918456.

The previous prime is 18918451. The next prime is 18918499. The reversal of 18918457 is 75481981.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13461561 + 5456896 = 3669^2 + 2336^2 .

It is a cyclic number.

It is not a de Polignac number, because 18918457 - 2¹¹ = 18916409 is a prime.

It is not a weakly prime, because it can be changed into another prime (18918451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9459228 + 9459229.

It is an arithmetic number, because the mean of its divisors is an integer number (9459229).

Almost surely, 2^18918457 is an apocalyptic number.

It is an amenable number.

18918457 is a deficient number, since it is larger than the sum of its proper divisors (1).

18918457 is an equidigital number, since it uses as much as digits as its factorization.

18918457 is an evil number, because the sum of its binary digits is even.

The product of its digits is 80640, while the sum is 43.

The square root of 18918457 is about 4349.5352625309. The cubic root of 18918457 is about 266.4578815408.

The spelling of 18918457 in words is "eighteen million, nine hundred eighteen thousand, four hundred fifty-seven".