21371518 has 8 divisors (see below), whose sum is σ = 36636912. Its totient is φ = 9159216.

The previous prime is 21371509. The next prime is 21371551. The reversal of 21371518 is 81517312.

It is a sphenic number, since it is the product of 3 distinct 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 in 3 ways as a sum of consecutive naturals, for example, 763255 + ... + 763282.

It is an arithmetic number, because the mean of its divisors is an integer number (4579614).

Almost surely, 2^21371518 is an apocalyptic number.

21371518 is a deficient number, since it is larger than the sum of its proper divisors (15265394).

21371518 is a wasteful number, since it uses less digits than its factorization.

21371518 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1526546.

The product of its digits is 1680, while the sum is 28.

The square root of 21371518 is about 4622.9339168974. The cubic root of 21371518 is about 277.5098846681.

It can be divided in two parts, 2137 and 1518, that added together give a triangular number (3655 = T₈₅).

The spelling of 21371518 in words is "twenty-one million, three hundred seventy-one thousand, five hundred eighteen".