21111212020 has 12 divisors (see below), whose sum is σ = 44333545284. Its totient is φ = 8444484800.

The previous prime is 21111211991. The next prime is 21111212053. The reversal of 21111212020 is 2021211112.

It can be written as a sum of positive squares in 2 ways, for example, as 7871948176 + 13239263844 = 88724^2 + 115062^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 527780281 + ... + 527780320.

It is an arithmetic number, because the mean of its divisors is an integer number (3694462107).

Almost surely, 2^21111212020 is an apocalyptic number.

21111212020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21111212020 is an abundant number, since it is smaller than the sum of its proper divisors (23222333264).

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

21111212020 is a wasteful number, since it uses less digits than its factorization.

21111212020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1055560610 (or 1055560608 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21111212020 its reverse (2021211112), we get a palindrome (23132423132).

The spelling of 21111212020 in words is "twenty-one billion, one hundred eleven million, two hundred twelve thousand, twenty".