21025042123 has 2 divisors, whose sum is σ = 21025042124. Its totient is φ = 21025042122.

The previous prime is 21025042121. The next prime is 21025042153. The reversal of 21025042123 is 32124052012.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21025042123 - 2¹ = 21025042121 is a prime.

Together with 21025042121, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 21025042094 and 21025042103.

It is not a weakly prime, because it can be changed into another prime (21025042121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10512521061 + 10512521062.

It is an arithmetic number, because the mean of its divisors is an integer number (10512521062).

Almost surely, 2^21025042123 is an apocalyptic number.

21025042123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21025042123 is an equidigital number, since it uses as much as digits as its factorization.

21025042123 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 960, while the sum is 22.

Adding to 21025042123 its reverse (32124052012), we get a palindrome (53149094135).

The spelling of 21025042123 in words is "twenty-one billion, twenty-five million, forty-two thousand, one hundred twenty-three".