21762749 has 2 divisors, whose sum is σ = 21762750. Its totient is φ = 21762748.

The previous prime is 21762743. The next prime is 21762757. The reversal of 21762749 is 94726712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20025625 + 1737124 = 4475^2 + 1318^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21762749 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21762743) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10881374 + 10881375.

It is an arithmetic number, because the mean of its divisors is an integer number (10881375).

Almost surely, 2^21762749 is an apocalyptic number.

It is an amenable number.

21762749 is a deficient number, since it is larger than the sum of its proper divisors (1).

21762749 is an equidigital number, since it uses as much as digits as its factorization.

21762749 is an evil number, because the sum of its binary digits is even.

The product of its digits is 42336, while the sum is 38.

The square root of 21762749 is about 4665.0561625773. The cubic root of 21762749 is about 279.1930379583.

The spelling of 21762749 in words is "twenty-one million, seven hundred sixty-two thousand, seven hundred forty-nine".