21815036 has 12 divisors (see below), whose sum is σ = 38214960. Its totient is φ = 10896480.

The previous prime is 21815033. The next prime is 21815039. The reversal of 21815036 is 63051812.

It is an interprime number because it is at equal distance from previous prime (21815033) and next prime (21815039).

It is a junction number, because it is equal to n+sod(n) for n = 21814996 and 21815014.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21815033) 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, 3041 + ... + 7271.

It is an arithmetic number, because the mean of its divisors is an integer number (3184580).

Almost surely, 2^21815036 is an apocalyptic number.

It is an amenable number.

21815036 is a deficient number, since it is larger than the sum of its proper divisors (16399924).

21815036 is a wasteful number, since it uses less digits than its factorization.

21815036 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5524 (or 5522 counting only the distinct ones).

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

The square root of 21815036 is about 4670.6569131119. The cubic root of 21815036 is about 279.4164547520.

Adding to 21815036 its reverse (63051812), we get a palindrome (84866848).

The spelling of 21815036 in words is "twenty-one million, eight hundred fifteen thousand, thirty-six".