21151318 has 4 divisors (see below), whose sum is σ = 31726980. Its totient is φ = 10575658.

The previous prime is 21151307. The next prime is 21151343. The reversal of 21151318 is 81315112.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 5287828 + ... + 5287831.

It is an arithmetic number, because the mean of its divisors is an integer number (7931745).

Almost surely, 2^21151318 is an apocalyptic number.

21151318 is a deficient number, since it is larger than the sum of its proper divisors (10575662).

21151318 is a wasteful number, since it uses less digits than its factorization.

21151318 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10575661.

The product of its digits is 240, while the sum is 22.

The square root of 21151318 is about 4599.0562075278. The cubic root of 21151318 is about 276.5534909106.

It can be divided in two parts, 211 and 51318, that added together give a square (51529 = 227²).

The spelling of 21151318 in words is "twenty-one million, one hundred fifty-one thousand, three hundred eighteen".