21745273 has 12 divisors (see below), whose sum is σ = 24730020. Its totient is φ = 19083680.

The previous prime is 21745247. The next prime is 21745279. The reversal of 21745273 is 37254712.

It can be written as a sum of positive squares in 2 ways, for example, as 9966649 + 11778624 = 3157^2 + 3432^2 .

It is not a de Polignac number, because 21745273 - 2⁹ = 21744761 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21745279) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 411 + ... + 6607.

It is an arithmetic number, because the mean of its divisors is an integer number (2060835).

Almost surely, 2^21745273 is an apocalyptic number.

It is an amenable number.

21745273 is a deficient number, since it is larger than the sum of its proper divisors (2984747).

21745273 is a wasteful number, since it uses less digits than its factorization.

21745273 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6248 (or 6237 counting only the distinct ones).

The product of its digits is 11760, while the sum is 31.

The square root of 21745273 is about 4663.1827114107. The cubic root of 21745273 is about 279.1182850836.

Adding to 21745273 its reverse (37254712), we get a palindrome (58999985).

It can be divided in two parts, 2174 and 5273, that added together give a palindrome (7447).

The spelling of 21745273 in words is "twenty-one million, seven hundred forty-five thousand, two hundred seventy-three".