18629881 has 2 divisors, whose sum is σ = 18629882. Its totient is φ = 18629880.

The previous prime is 18629869. The next prime is 18629887. The reversal of 18629881 is 18892681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18627856 + 2025 = 4316^2 + 45^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18629881 is a prime.

It is a super-2 number, since 2×18629881² = 694144932148322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (18629887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9314940 + 9314941.

It is an arithmetic number, because the mean of its divisors is an integer number (9314941).

Almost surely, 2^18629881 is an apocalyptic number.

It is an amenable number.

18629881 is a deficient number, since it is larger than the sum of its proper divisors (1).

18629881 is an equidigital number, since it uses as much as digits as its factorization.

18629881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 55296, while the sum is 43.

The square root of 18629881 is about 4316.2345858398. The cubic root of 18629881 is about 265.0961132317.

The spelling of 18629881 in words is "eighteen million, six hundred twenty-nine thousand, eight hundred eighty-one".