21318051 has 16 divisors (see below), whose sum is σ = 30288384. Its totient is φ = 13290624.

The previous prime is 21318047. The next prime is 21318091. The reversal of 21318051 is 15081312.

It is not a de Polignac number, because 21318051 - 2² = 21318047 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21318091) 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 15 ways as a sum of consecutive naturals, for example, 7266 + ... + 9768.

It is an arithmetic number, because the mean of its divisors is an integer number (1893024).

Almost surely, 2^21318051 is an apocalyptic number.

21318051 is a deficient number, since it is larger than the sum of its proper divisors (8970333).

21318051 is a wasteful number, since it uses less digits than its factorization.

21318051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2690.

The product of its (nonzero) digits is 240, while the sum is 21.

The square root of 21318051 is about 4617.1474960196. The cubic root of 21318051 is about 277.2782678068.

Adding to 21318051 its reverse (15081312), we get a palindrome (36399363).

The spelling of 21318051 in words is "twenty-one million, three hundred eighteen thousand, fifty-one".