21212323231 has 4 divisors (see below), whose sum is σ = 23140716264. Its totient is φ = 19283930200.

The previous prime is 21212323219. The next prime is 21212323243. The reversal of 21212323231 is 13232321212.

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

It is an interprime number because it is at equal distance from previous prime (21212323219) and next prime (21212323243).

It is a cyclic number.

It is not a de Polignac number, because 21212323231 - 2⁷ = 21212323103 is a prime.

It is a super-2 number, since 2×21212323231² (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 (21212323271) 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, 964196500 + ... + 964196521.

It is an arithmetic number, because the mean of its divisors is an integer number (5785179066).

Almost surely, 2^21212323231 is an apocalyptic number.

21212323231 is a deficient number, since it is larger than the sum of its proper divisors (1928393033).

21212323231 is a wasteful number, since it uses less digits than its factorization.

21212323231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1928393032.

The product of its digits is 864, while the sum is 22.

Adding to 21212323231 its reverse (13232321212), we get a palindrome (34444644443).

It can be divided in two parts, 21212 and 323231, that added together give a palindrome (344443).

The spelling of 21212323231 in words is "twenty-one billion, two hundred twelve million, three hundred twenty-three thousand, two hundred thirty-one".