21210010020 has 36 divisors (see below), whose sum is σ = 64337030940. Its totient is φ = 5656002624.

The previous prime is 21210009959. The next prime is 21210010039. The reversal of 21210010020 is 2001001212.

It can be written as a sum of positive squares in 2 ways, for example, as 16435752804 + 4774257216 = 128202^2 + 69096^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21210009984 and 21210010011.

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, 58916515 + ... + 58916874.

Almost surely, 2^21210010020 is an apocalyptic number.

21210010020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21210010020 is an abundant number, since it is smaller than the sum of its proper divisors (43127020920).

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

21210010020 is a wasteful number, since it uses less digits than its factorization.

21210010020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117833404 (or 117833399 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21210010020 its reverse (2001001212), we get a palindrome (23211011232).

The spelling of 21210010020 in words is "twenty-one billion, two hundred ten million, ten thousand, twenty".