21518036 has 12 divisors (see below), whose sum is σ = 37711380. Its totient is φ = 10743360.

The previous prime is 21518033. The next prime is 21518047. The reversal of 21518036 is 63081512.

It can be written as a sum of positive squares in 2 ways, for example, as 2421136 + 19096900 = 1556^2 + 4370^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21517996 and 21518014.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21518033) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 491 + ... + 6578.

It is an arithmetic number, because the mean of its divisors is an integer number (3142615).

Almost surely, 2^21518036 is an apocalyptic number.

It is an amenable number.

21518036 is a deficient number, since it is larger than the sum of its proper divisors (16193344).

21518036 is a wasteful number, since it uses less digits than its factorization.

21518036 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7834 (or 7832 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 21518036 is about 4638.7537119360. The cubic root of 21518036 is about 278.1426212965.

Adding to 21518036 its reverse (63081512), we get a palindrome (84599548).

The spelling of 21518036 in words is "twenty-one million, five hundred eighteen thousand, thirty-six".