21057743 has 8 divisors (see below), whose sum is σ = 24256512. Its totient is φ = 17906616.

The previous prime is 21057731. The next prime is 21057763. The reversal of 21057743 is 34775012.

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

It is not a de Polignac number, because 21057743 - 2⁴ = 21057727 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21057763) 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 7 ways as a sum of consecutive naturals, for example, 10955 + ... + 12732.

It is an arithmetic number, because the mean of its divisors is an integer number (3032064).

Almost surely, 2^21057743 is an apocalyptic number.

21057743 is a deficient number, since it is larger than the sum of its proper divisors (3198769).

21057743 is a wasteful number, since it uses less digits than its factorization.

21057743 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23821.

The product of its (nonzero) digits is 5880, while the sum is 29.

The square root of 21057743 is about 4588.8716478019. The cubic root of 21057743 is about 276.1450569496.

The spelling of 21057743 in words is "twenty-one million, fifty-seven thousand, seven hundred forty-three".