21742273 has 16 divisors (see below), whose sum is σ = 25759744. Its totient is φ = 17962560.

The previous prime is 21742271. The next prime is 21742307. The reversal of 21742273 is 37224712.

It is not a de Polignac number, because 21742273 - 2¹ = 21742271 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21742271) 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 15 ways as a sum of consecutive naturals, for example, 32563 + ... + 33223.

It is an arithmetic number, because the mean of its divisors is an integer number (1609984).

Almost surely, 2^21742273 is an apocalyptic number.

It is an amenable number.

21742273 is a deficient number, since it is larger than the sum of its proper divisors (4017471).

21742273 is a wasteful number, since it uses less digits than its factorization.

21742273 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 832.

The product of its digits is 4704, while the sum is 28.

The square root of 21742273 is about 4662.8610315985. The cubic root of 21742273 is about 279.1054486790.

Adding to 21742273 its reverse (37224712), we get a palindrome (58966985).

The spelling of 21742273 in words is "twenty-one million, seven hundred forty-two thousand, two hundred seventy-three".