21232516 has 12 divisors (see below), whose sum is σ = 37300032. Its totient is φ = 10575368.

The previous prime is 21232513. The next prime is 21232531. The reversal of 21232516 is 61523212.

It is not an unprimeable number, because it can be changed into a prime (21232511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9040 + ... + 11143.

It is an arithmetic number, because the mean of its divisors is an integer number (3108336).

Almost surely, 2^21232516 is an apocalyptic number.

It is an amenable number.

21232516 is a deficient number, since it is larger than the sum of its proper divisors (16067516).

21232516 is a wasteful number, since it uses less digits than its factorization.

21232516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20450 (or 20448 counting only the distinct ones).

The product of its digits is 720, while the sum is 22.

The square root of 21232516 is about 4607.8754323441. The cubic root of 21232516 is about 276.9069269863.

Adding to 21232516 its reverse (61523212), we get a palindrome (82755728).

The spelling of 21232516 in words is "twenty-one million, two hundred thirty-two thousand, five hundred sixteen".