21312212021 has 16 divisors (see below), whose sum is σ = 21618188736. Its totient is φ = 21009010176.

The previous prime is 21312211951. The next prime is 21312212093. The reversal of 21312212021 is 12021221312.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21312212021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21312212821) 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, 18977366 + ... + 18978488.

It is an arithmetic number, because the mean of its divisors is an integer number (1351136796).

Almost surely, 2^21312212021 is an apocalyptic number.

It is an amenable number.

21312212021 is a deficient number, since it is larger than the sum of its proper divisors (305976715).

21312212021 is a wasteful number, since it uses less digits than its factorization.

21312212021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2132.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 21312212021 its reverse (12021221312), we get a palindrome (33333433333).

The spelling of 21312212021 in words is "twenty-one billion, three hundred twelve million, two hundred twelve thousand, twenty-one".