21752645 has 8 divisors (see below), whose sum is σ = 26131704. Its totient is φ = 17383104.

The previous prime is 21752611. The next prime is 21752657. The reversal of 21752645 is 54625712.

It can be written as a sum of positive squares in 4 ways, for example, as 10042561 + 11710084 = 3169^2 + 3422^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21752645 - 2¹⁰ = 21751621 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4427 + ... + 7943.

It is an arithmetic number, because the mean of its divisors is an integer number (3266463).

Almost surely, 2^21752645 is an apocalyptic number.

It is an amenable number.

21752645 is a deficient number, since it is larger than the sum of its proper divisors (4379059).

21752645 is a wasteful number, since it uses less digits than its factorization.

21752645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4759.

The product of its digits is 16800, while the sum is 32.

The square root of 21752645 is about 4663.9730916891. The cubic root of 21752645 is about 279.1498233941.

The spelling of 21752645 in words is "twenty-one million, seven hundred fifty-two thousand, six hundred forty-five".