21018316 has 24 divisors (see below), whose sum is σ = 40887504. Its totient is φ = 9372480.

The previous prime is 21018293. The next prime is 21018317. The reversal of 21018316 is 61381012.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is not an unprimeable number, because it can be changed into a prime (21018317) 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 7 ways as a sum of consecutive naturals, for example, 2175 + ... + 6838.

It is an arithmetic number, because the mean of its divisors is an integer number (1703646).

Almost surely, 2^21018316 is an apocalyptic number.

It is an amenable number.

21018316 is a deficient number, since it is larger than the sum of its proper divisors (19869188).

21018316 is a wasteful number, since it uses less digits than its factorization.

21018316 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9081 (or 9079 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 21018316 is about 4584.5736988296. The cubic root of 21018316 is about 275.9726045762.

Adding to 21018316 its reverse (61381012), we get a palindrome (82399328).

The spelling of 21018316 in words is "twenty-one million, eighteen thousand, three hundred sixteen".