21212020331 has 4 divisors (see below), whose sum is σ = 21213660432. Its totient is φ = 21210380232.

The previous prime is 21212020267. The next prime is 21212020369. The reversal of 21212020331 is 13302021212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21212020331 - 2⁶ = 21212020267 is a prime.

It is a super-3 number, since 3×21212020331³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21212020381) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 800495 + ... + 826568.

It is an arithmetic number, because the mean of its divisors is an integer number (5303415108).

Almost surely, 2^21212020331 is an apocalyptic number.

21212020331 is a deficient number, since it is larger than the sum of its proper divisors (1640101).

21212020331 is a wasteful number, since it uses less digits than its factorization.

21212020331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1640100.

The product of its (nonzero) digits is 144, while the sum is 17.

Adding to 21212020331 its reverse (13302021212), we get a palindrome (34514041543).

The spelling of 21212020331 in words is "twenty-one billion, two hundred twelve million, twenty thousand, three hundred thirty-one".