18630881 has 4 divisors (see below), whose sum is σ = 18725652. Its totient is φ = 18536112.

The previous prime is 18630877. The next prime is 18630901. The reversal of 18630881 is 18803681.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18803681 = 13 ⋅1446437.

It can be written as a sum of positive squares in 2 ways, for example, as 18318400 + 312481 = 4280^2 + 559^2 .

It is a cyclic number.

It is not a de Polignac number, because 18630881 - 2² = 18630877 is a prime.

It is a super-2 number, since 2×18630881² = 694219453672322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18632881) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47090 + ... + 47483.

It is an arithmetic number, because the mean of its divisors is an integer number (4681413).

Almost surely, 2^18630881 is an apocalyptic number.

It is an amenable number.

18630881 is a deficient number, since it is larger than the sum of its proper divisors (94771).

18630881 is an equidigital number, since it uses as much as digits as its factorization.

18630881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94770.

The product of its (nonzero) digits is 9216, while the sum is 35.

The square root of 18630881 is about 4316.3504259965. The cubic root of 18630881 is about 265.1008563533.

The spelling of 18630881 in words is "eighteen million, six hundred thirty thousand, eight hundred eighty-one".