21752749 has 4 divisors (see below), whose sum is σ = 21772800. Its totient is φ = 21732700.

The previous prime is 21752747. The next prime is 21752791. The reversal of 21752749 is 94725712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21752749 - 2¹ = 21752747 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21752747) 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, 8299 + ... + 10600.

It is an arithmetic number, because the mean of its divisors is an integer number (5443200).

Almost surely, 2^21752749 is an apocalyptic number.

It is an amenable number.

21752749 is a deficient number, since it is larger than the sum of its proper divisors (20051).

21752749 is a wasteful number, since it uses less digits than its factorization.

21752749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20050.

The product of its digits is 35280, while the sum is 37.

The square root of 21752749 is about 4663.9842409682. The cubic root of 21752749 is about 279.1502682677.

The spelling of 21752749 in words is "twenty-one million, seven hundred fifty-two thousand, seven hundred forty-nine".