21221183616 has 64 divisors (see below), whose sum is σ = 57292910400. Its totient is φ = 6957757440.

The previous prime is 21221183591. The next prime is 21221183617. The reversal of 21221183616 is 61638112212.

It is a tau number, because it is divible by the number of its divisors (64).

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

It is not an unprimeable number, because it can be changed into a prime (21221183617) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 429556 + ... + 476403.

It is an arithmetic number, because the mean of its divisors is an integer number (895201725).

Almost surely, 2^21221183616 is an apocalyptic number.

It is an amenable number.

21221183616 is an abundant number, since it is smaller than the sum of its proper divisors (36071726784).

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

21221183616 is an equidigital number, since it uses as much as digits as its factorization.

21221183616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 906037 (or 906025 counting only the distinct ones).

The product of its digits is 6912, while the sum is 33.

Adding to 21221183616 its reverse (61638112212), we get a palindrome (82859295828).

The spelling of 21221183616 in words is "twenty-one billion, two hundred twenty-one million, one hundred eighty-three thousand, six hundred sixteen".