21216221420 has 24 divisors (see below), whose sum is σ = 45181590048. Its totient is φ = 8366960000.

The previous prime is 21216221419. The next prime is 21216221431. The reversal of 21216221420 is 2412261212.

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, 7469081 + ... + 7471920.

It is an arithmetic number, because the mean of its divisors is an integer number (1882566252).

Almost surely, 2^21216221420 is an apocalyptic number.

21216221420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21216221420 is an abundant number, since it is smaller than the sum of its proper divisors (23965368628).

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

21216221420 is a wasteful number, since it uses less digits than its factorization.

21216221420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14941081 (or 14941079 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 23.

Adding to 21216221420 its reverse (2412261212), we get a palindrome (23628482632).

The spelling of 21216221420 in words is "twenty-one billion, two hundred sixteen million, two hundred twenty-one thousand, four hundred twenty".