21634518 has 16 divisors (see below), whose sum is σ = 43351920. Its totient is φ = 7197696.

The previous prime is 21634453. The next prime is 21634537. The reversal of 21634518 is 81543612.

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 7 ways as a sum of consecutive naturals, for example, 246 + ... + 6582.

It is an arithmetic number, because the mean of its divisors is an integer number (2709495).

Almost surely, 2^21634518 is an apocalyptic number.

21634518 is an abundant number, since it is smaller than the sum of its proper divisors (21717402).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21634518 is a wasteful number, since it uses less digits than its factorization.

21634518 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6911.

The product of its digits is 5760, while the sum is 30.

The square root of 21634518 is about 4651.2920785519. The cubic root of 21634518 is about 278.6436013993.

The spelling of 21634518 in words is "twenty-one million, six hundred thirty-four thousand, five hundred eighteen".