21202102123 has 4 divisors (see below), whose sum is σ = 21204891808. Its totient is φ = 21199312440.

The previous prime is 21202102111. The next prime is 21202102153. The reversal of 21202102123 is 32120120212.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21202102123 - 2⁹ = 21202101611 is a prime.

It is a super-2 number, since 2×21202102123² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21202102097 and 21202102106.

It is not an unprimeable number, because it can be changed into a prime (21202102153) 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, 1383411 + ... + 1398652.

It is an arithmetic number, because the mean of its divisors is an integer number (5301222952).

Almost surely, 2^21202102123 is an apocalyptic number.

21202102123 is a deficient number, since it is larger than the sum of its proper divisors (2789685).

21202102123 is an equidigital number, since it uses as much as digits as its factorization.

21202102123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2789684.

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21202102123 its reverse (32120120212), we get a palindrome (53322222335).

The spelling of 21202102123 in words is "twenty-one billion, two hundred two million, one hundred two thousand, one hundred twenty-three".