21123116 has 36 divisors (see below), whose sum is σ = 43934688. Its totient is φ = 8856288.

The previous prime is 21123103. The next prime is 21123119. The reversal of 21123116 is 61132112.

It is a junction number, because it is equal to n+sod(n) for n = 21123094 and 21123103.

It is not an unprimeable number, because it can be changed into a prime (21123119) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8066 + ... + 10358.

It is an arithmetic number, because the mean of its divisors is an integer number (1220408).

Almost surely, 2^21123116 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21123116, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21967344).

21123116 is an abundant number, since it is smaller than the sum of its proper divisors (22811572).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21123116 is a wasteful number, since it uses less digits than its factorization.

21123116 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2358 (or 2349 counting only the distinct ones).

The product of its digits is 72, while the sum is 17.

The square root of 21123116 is about 4595.9891209619. The cubic root of 21123116 is about 276.4305225211.

Adding to 21123116 its reverse (61132112), we get a palindrome (82255228).

The spelling of 21123116 in words is "twenty-one million, one hundred twenty-three thousand, one hundred sixteen".