21212212020 has 48 divisors (see below), whose sum is σ = 60657907968. Its totient is φ = 5536236160.

The previous prime is 21212211989. The next prime is 21212212037. The reversal of 21212212020 is 2021221212.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3758211 + ... + 3763850.

It is an arithmetic number, because the mean of its divisors is an integer number (1263706416).

Almost surely, 2^21212212020 is an apocalyptic number.

21212212020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21212212020 is an abundant number, since it is smaller than the sum of its proper divisors (39445695948).

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

21212212020 is a wasteful number, since it uses less digits than its factorization.

21212212020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7522120 (or 7522118 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21212212020 its reverse (2021221212), we get a palindrome (23233433232).

The spelling of 21212212020 in words is "twenty-one billion, two hundred twelve million, two hundred twelve thousand, twenty".