21123010231 has 2 divisors, whose sum is σ = 21123010232. Its totient is φ = 21123010230.

The previous prime is 21123010229. The next prime is 21123010247. The reversal of 21123010231 is 13201032112.

It is an a-pointer prime, because the next prime (21123010247) can be obtained adding 21123010231 to its sum of digits (16).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21123010231 - 2¹ = 21123010229 is a prime.

It is a super-2 number, since 2×21123010231² (a number of 21 digits) contains 22 as substring.

Together with 21123010229, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21123010261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561505115 + 10561505116.

It is an arithmetic number, because the mean of its divisors is an integer number (10561505116).

Almost surely, 2^21123010231 is an apocalyptic number.

21123010231 is a deficient number, since it is larger than the sum of its proper divisors (1).

21123010231 is an equidigital number, since it uses as much as digits as its factorization.

21123010231 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 21123010231 its reverse (13201032112), we get a palindrome (34324042343).

The spelling of 21123010231 in words is "twenty-one billion, one hundred twenty-three million, ten thousand, two hundred thirty-one".