18475781 has 2 divisors, whose sum is σ = 18475782. Its totient is φ = 18475780.

The previous prime is 18475763. The next prime is 18475801. The reversal of 18475781 is 18757481.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17556100 + 919681 = 4190^2 + 959^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18475781 is a prime.

It is a super-2 number, since 2×18475781² = 682708967119922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18475081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9237890 + 9237891.

It is an arithmetic number, because the mean of its divisors is an integer number (9237891).

Almost surely, 2^18475781 is an apocalyptic number.

It is an amenable number.

18475781 is a deficient number, since it is larger than the sum of its proper divisors (1).

18475781 is an equidigital number, since it uses as much as digits as its factorization.

18475781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 62720, while the sum is 41.

The square root of 18475781 is about 4298.3463099197. The cubic root of 18475781 is about 264.3631604815.

The spelling of 18475781 in words is "eighteen million, four hundred seventy-five thousand, seven hundred eighty-one".