21216213624 has 32 divisors (see below), whose sum is σ = 53315367120. Its totient is φ = 7035426816.

The previous prime is 21216213593. The next prime is 21216213649. The reversal of 21216213624 is 42631261212.

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 21216213591 and 21216213600.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2285547 + ... + 2294810.

Almost surely, 2^21216213624 is an apocalyptic number.

21216213624 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21216213624 is an abundant number, since it is smaller than the sum of its proper divisors (32099153496).

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

21216213624 is a wasteful number, since it uses less digits than its factorization.

21216213624 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4580559 (or 4580555 counting only the distinct ones).

The product of its digits is 6912, while the sum is 30.

Adding to 21216213624 its reverse (42631261212), we get a palindrome (63847474836).

The spelling of 21216213624 in words is "twenty-one billion, two hundred sixteen million, two hundred thirteen thousand, six hundred twenty-four".