21218000000 has 168 divisors, whose sum is σ = 53355078765. Its totient is φ = 8404800000.

The previous prime is 21217999991. The next prime is 21218000009. The reversal of 21218000000 is 81212.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It is an interprime number because it is at equal distance from previous prime (21217999991) and next prime (21218000009).

It can be written as a sum of positive squares in 4 ways, for example, as 3618263104 + 17599736896 = 60152^2 + 132664^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=103000.

It is not an unprimeable number, because it can be changed into a prime (21218000009) by changing a digit.

It is a polite number, since it can be written in 20 ways as a sum of consecutive naturals, for example, 205999949 + ... + 206000051.

Almost surely, 2^21218000000 is an apocalyptic number.

21218000000 is a gapful number since it is divisible by the number (20) 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 21218000000

21218000000 is an abundant number, since it is smaller than the sum of its proper divisors (32137078765).

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

21218000000 is an frugal number, since it uses more digits than its factorization.

21218000000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 250 (or 110 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Multiplying 21218000000 by its product of nonzero digits (32), we get a square (678976000000 = 824000²).

21218000000 divided by its product of nonzero digits (32) gives a square (663062500 = 25750²).

Adding to 21218000000 its reverse (81212), we get a palindrome (21218081212).

The spelling of 21218000000 in words is "twenty-one billion, two hundred eighteen million", and thus it is an aban number.