21212023031 has 4 divisors (see below), whose sum is σ = 21212967864. Its totient is φ = 21211078200.

The previous prime is 21212023009. The next prime is 21212023043. The reversal of 21212023031 is 13032021212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21212023031 is a prime.

It is a super-2 number, since 2×21212023031² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212023331) by changing a digit.

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, 437900 + ... + 483921.

It is an arithmetic number, because the mean of its divisors is an integer number (5303241966).

Almost surely, 2^21212023031 is an apocalyptic number.

21212023031 is a deficient number, since it is larger than the sum of its proper divisors (944833).

21212023031 is an equidigital number, since it uses as much as digits as its factorization.

21212023031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 944832.

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

Adding to 21212023031 its reverse (13032021212), we get a palindrome (34244044243).

The spelling of 21212023031 in words is "twenty-one billion, two hundred twelve million, twenty-three thousand, thirty-one".