18745681 has 2 divisors, whose sum is σ = 18745682. Its totient is φ = 18745680.

The previous prime is 18745631. The next prime is 18745693. The reversal of 18745681 is 18654781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15563025 + 3182656 = 3945^2 + 1784^2 .

It is a cyclic number.

It is not a de Polignac number, because 18745681 - 2¹³ = 18737489 is a prime.

It is a super-2 number, since 2×18745681² = 702801112307522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (18745631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9372840 + 9372841.

It is an arithmetic number, because the mean of its divisors is an integer number (9372841).

Almost surely, 2^18745681 is an apocalyptic number.

It is an amenable number.

18745681 is a deficient number, since it is larger than the sum of its proper divisors (1).

18745681 is an equidigital number, since it uses as much as digits as its factorization.

18745681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 53760, while the sum is 40.

The square root of 18745681 is about 4329.6282750370. The cubic root of 18745681 is about 265.6442424076.

The spelling of 18745681 in words is "eighteen million, seven hundred forty-five thousand, six hundred eighty-one".