21985743 has 16 divisors (see below), whose sum is σ = 33427296. Its totient is φ = 12733440.

The previous prime is 21985703. The next prime is 21985753. The reversal of 21985743 is 34758912.

It is not a de Polignac number, because 21985743 - 2¹⁰ = 21984719 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21985703) 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 15 ways as a sum of consecutive naturals, for example, 15918 + ... + 17243.

It is an arithmetic number, because the mean of its divisors is an integer number (2089206).

Almost surely, 2^21985743 is an apocalyptic number.

21985743 is a deficient number, since it is larger than the sum of its proper divisors (11441553).

21985743 is a wasteful number, since it uses less digits than its factorization.

21985743 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33194.

The product of its digits is 60480, while the sum is 39.

The square root of 21985743 is about 4688.8957122120. The cubic root of 21985743 is about 280.1433916907.

The spelling of 21985743 in words is "twenty-one million, nine hundred eighty-five thousand, seven hundred forty-three".