18440831 has 2 divisors, whose sum is σ = 18440832. Its totient is φ = 18440830.

The previous prime is 18440813. The next prime is 18440833. The reversal of 18440831 is 13804481.

Together with previous prime (18440813) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is an emirp because it is prime and its reverse (13804481) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18440831 is a prime.

It is a super-2 number, since 2×18440831² = 680128495941122, which contains 22 as substring.

Together with 18440833, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 18440794 and 18440803.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18440833) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9220415 + 9220416.

It is an arithmetic number, because the mean of its divisors is an integer number (9220416).

Almost surely, 2^18440831 is an apocalyptic number.

18440831 is a deficient number, since it is larger than the sum of its proper divisors (1).

18440831 is an equidigital number, since it uses as much as digits as its factorization.

18440831 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3072, while the sum is 29.

The square root of 18440831 is about 4294.2788684481. The cubic root of 18440831 is about 264.1963596915.

The spelling of 18440831 in words is "eighteen million, four hundred forty thousand, eight hundred thirty-one".