21171742 has 8 divisors (see below), whose sum is σ = 31781232. Its totient is φ = 10578000.

The previous prime is 21171739. The next prime is 21171743. The reversal of 21171742 is 24717112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21171743) 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 3 ways as a sum of consecutive naturals, for example, 367 + ... + 6517.

It is an arithmetic number, because the mean of its divisors is an integer number (3972654).

Almost surely, 2^21171742 is an apocalyptic number.

21171742 is a deficient number, since it is larger than the sum of its proper divisors (10609490).

21171742 is a wasteful number, since it uses less digits than its factorization.

21171742 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7874.

The product of its digits is 784, while the sum is 25.

The square root of 21171742 is about 4601.2761273369. The cubic root of 21171742 is about 276.6424768774.

Adding to 21171742 its reverse (24717112), we get a palindrome (45888854).

The spelling of 21171742 in words is "twenty-one million, one hundred seventy-one thousand, seven hundred forty-two".