18221712 has 80 divisors (see below), whose sum is σ = 49496832. Its totient is φ = 5770240.

The previous prime is 18221711. The next prime is 18221717. The reversal of 18221712 is 21712281.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (18221711) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 92398 + ... + 92594.

Almost surely, 2^18221712 is an apocalyptic number.

18221712 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 18221712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24748416).

18221712 is an abundant number, since it is smaller than the sum of its proper divisors (31275120).

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

18221712 is a wasteful number, since it uses less digits than its factorization.

18221712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 296 (or 290 counting only the distinct ones).

The product of its digits is 448, while the sum is 24.

The square root of 18221712 is about 4268.6897287107. The cubic root of 18221712 is about 263.1457696926.

Adding to 18221712 its reverse (21712281), we get a palindrome (39933993).

The spelling of 18221712 in words is "eighteen million, two hundred twenty-one thousand, seven hundred twelve".