18561312 has 288 divisors, whose sum is σ = 70447104. Its totient is φ = 4665600.

The previous prime is 18561307. The next prime is 18561313. The reversal of 18561312 is 21316581.

It is a tau number, because it is divible by the number of its divisors (288).

It is a super-2 number, since 2×18561312² = 689044606322688, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18561313) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 598737 + ... + 598767.

It is an arithmetic number, because the mean of its divisors is an integer number (244608).

Almost surely, 2^18561312 is an apocalyptic number.

18561312 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18561312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35223552).

18561312 is an abundant number, since it is smaller than the sum of its proper divisors (51885792).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18561312 is a wasteful number, since it uses less digits than its factorization.

18561312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74 (or 54 counting only the distinct ones).

The product of its digits is 1440, while the sum is 27.

The square root of 18561312 is about 4308.2841131940. The cubic root of 18561312 is about 264.7704764716.

Adding to 18561312 its reverse (21316581), we get a palindrome (39877893).

The spelling of 18561312 in words is "eighteen million, five hundred sixty-one thousand, three hundred twelve".