21420420100 has 18 divisors (see below), whose sum is σ = 46482311834. Its totient is φ = 8568168000.

The previous prime is 21420420097. The next prime is 21420420103. The reversal of 21420420100 is 102402412.

It is an interprime number because it is at equal distance from previous prime (21420420097) and next prime (21420420103).

It can be written as a sum of positive squares in 3 ways, for example, as 725871364 + 20694548736 = 26942^2 + 143856^2 .

It is not an unprimeable number, because it can be changed into a prime (21420420103) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 107102001 + ... + 107102200.

Almost surely, 2^21420420100 is an apocalyptic number.

21420420100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21420420100 is an abundant number, since it is smaller than the sum of its proper divisors (25061891734).

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

21420420100 is a wasteful number, since it uses less digits than its factorization.

21420420100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214204215 (or 214204208 counting only the distinct ones).

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

Adding to 21420420100 its reverse (102402412), we get a palindrome (21522822512).

The spelling of 21420420100 in words is "twenty-one billion, four hundred twenty million, four hundred twenty thousand, one hundred".