18493813 has 4 divisors (see below), whose sum is σ = 19916428. Its totient is φ = 17071200.

The previous prime is 18493781. The next prime is 18493823. The reversal of 18493813 is 31839481.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31839481 = 283 ⋅112507.

It can be written as a sum of positive squares in 2 ways, for example, as 7879249 + 10614564 = 2807^2 + 3258^2 .

It is a cyclic number.

It is not a de Polignac number, because 18493813 - 2⁵ = 18493781 is a prime.

It is a super-2 number, since 2×18493813² = 684042238557938, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18493823) 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, 711288 + ... + 711313.

It is an arithmetic number, because the mean of its divisors is an integer number (4979107).

Almost surely, 2^18493813 is an apocalyptic number.

18493813 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

It is an amenable number.

18493813 is a deficient number, since it is larger than the sum of its proper divisors (1422615).

18493813 is a wasteful number, since it uses less digits than its factorization.

18493813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1422614.

The product of its digits is 20736, while the sum is 37.

The square root of 18493813 is about 4300.4433492374. The cubic root of 18493813 is about 264.4491369376.

It can be divided in two parts, 18493 and 813, that added together give a triangular number (19306 = T₁₉₆).

The spelling of 18493813 in words is "eighteen million, four hundred ninety-three thousand, eight hundred thirteen".