21744725749 has 4 divisors (see below), whose sum is σ = 21746110860. Its totient is φ = 21743340640.

The previous prime is 21744725669. The next prime is 21744725759. The reversal of 21744725749 is 94752744712.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12371000625 + 9373725124 = 111225^2 + 96818^2 .

It is a cyclic number.

It is not a de Polignac number, because 21744725749 - 2²¹ = 21742628597 is a prime.

It is a super-2 number, since 2×21744725749² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21744725696 and 21744725705.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21744725759) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 668734 + ... + 700495.

It is an arithmetic number, because the mean of its divisors is an integer number (5436527715).

Almost surely, 2^21744725749 is an apocalyptic number.

It is an amenable number.

21744725749 is a deficient number, since it is larger than the sum of its proper divisors (1385111).

21744725749 is a wasteful number, since it uses less digits than its factorization.

21744725749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1385110.

The product of its digits is 3951360, while the sum is 52.

The spelling of 21744725749 in words is "twenty-one billion, seven hundred forty-four million, seven hundred twenty-five thousand, seven hundred forty-nine".