21749718 has 16 divisors (see below), whose sum is σ = 45789120. Its totient is φ = 6868296.

The previous prime is 21749713. The next prime is 21749719. The reversal of 21749718 is 81794712.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21749713) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 95280 + ... + 95507.

It is an arithmetic number, because the mean of its divisors is an integer number (2861820).

Almost surely, 2^21749718 is an apocalyptic number.

21749718 is an abundant number, since it is smaller than the sum of its proper divisors (24039402).

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

21749718 is a wasteful number, since it uses less digits than its factorization.

21749718 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 190811.

The product of its digits is 28224, while the sum is 39.

The square root of 21749718 is about 4663.6592928729. The cubic root of 21749718 is about 279.1373021860.

The spelling of 21749718 in words is "twenty-one million, seven hundred forty-nine thousand, seven hundred eighteen".