21240420100 has 36 divisors (see below), whose sum is σ = 46385323684. Its totient is φ = 8442046080.

The previous prime is 21240420073. The next prime is 21240420209. The reversal of 21240420100 is 102404212.

It can be written as a sum of positive squares in 6 ways, for example, as 349764804 + 20890655296 = 18702^2 + 144536^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 660747 + ... + 692146.

Almost surely, 2^21240420100 is an apocalyptic number.

21240420100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21240420100 is an abundant number, since it is smaller than the sum of its proper divisors (25144903584).

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

21240420100 is a wasteful number, since it uses less digits than its factorization.

21240420100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1353064 (or 1353057 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 16.

Adding to 21240420100 its reverse (102404212), we get a palindrome (21342824312).

The spelling of 21240420100 in words is "twenty-one billion, two hundred forty million, four hundred twenty thousand, one hundred".