21103121623 has 2 divisors, whose sum is σ = 21103121624. Its totient is φ = 21103121622.

The previous prime is 21103121597. The next prime is 21103121659. The reversal of 21103121623 is 32612130112.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21103121623 - 2¹³ = 21103113431 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21103121594 and 21103121603.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21103127623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551560811 + 10551560812.

It is an arithmetic number, because the mean of its divisors is an integer number (10551560812).

Almost surely, 2^21103121623 is an apocalyptic number.

21103121623 is a deficient number, since it is larger than the sum of its proper divisors (1).

21103121623 is an equidigital number, since it uses as much as digits as its factorization.

21103121623 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 22.

Adding to 21103121623 its reverse (32612130112), we get a palindrome (53715251735).

The spelling of 21103121623 in words is "twenty-one billion, one hundred three million, one hundred twenty-one thousand, six hundred twenty-three".