21212312020 has 48 divisors (see below), whose sum is σ = 47939462928. Its totient is φ = 7854888960.

The previous prime is 21212311997. The next prime is 21212312029. The reversal of 21212312020 is 2021321212.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 21104836 + 21191207184 = 4594^2 + 145572^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21212311985 and 21212312003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212312029) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 490647 + ... + 532126.

It is an arithmetic number, because the mean of its divisors is an integer number (998738811).

Almost surely, 2^21212312020 is an apocalyptic number.

21212312020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21212312020 is an abundant number, since it is smaller than the sum of its proper divisors (26727150908).

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

21212312020 is a wasteful number, since it uses less digits than its factorization.

21212312020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1022860 (or 1022858 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21212312020 its reverse (2021321212), we get a palindrome (23233633232).

The spelling of 21212312020 in words is "twenty-one billion, two hundred twelve million, three hundred twelve thousand, twenty".