21210200020 has 24 divisors (see below), whose sum is σ = 44544334464. Its totient is φ = 8483524896.

The previous prime is 21210199999. The next prime is 21210200021. The reversal of 21210200020 is 2000201212.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210200021) 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, 431209 + ... + 477871.

It is an arithmetic number, because the mean of its divisors is an integer number (1856013936).

Almost surely, 2^21210200020 is an apocalyptic number.

21210200020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21210200020 is an abundant number, since it is smaller than the sum of its proper divisors (23334134444).

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

21210200020 is a wasteful number, since it uses less digits than its factorization.

21210200020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69399 (or 69397 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

Adding to 21210200020 its reverse (2000201212), we get a palindrome (23210401232).

The spelling of 21210200020 in words is "twenty-one billion, two hundred ten million, two hundred thousand, twenty".