21849749 has 2 divisors, whose sum is σ = 21849750. Its totient is φ = 21849748.

The previous prime is 21849739. The next prime is 21849757. The reversal of 21849749 is 94794812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12909649 + 8940100 = 3593^2 + 2990^2 .

It is a cyclic number.

It is not a de Polignac number, because 21849749 - 2⁴ = 21849733 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21849739) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10924874 + 10924875.

It is an arithmetic number, because the mean of its divisors is an integer number (10924875).

Almost surely, 2^21849749 is an apocalyptic number.

It is an amenable number.

21849749 is a deficient number, since it is larger than the sum of its proper divisors (1).

21849749 is an equidigital number, since it uses as much as digits as its factorization.

21849749 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145152, while the sum is 44.

The square root of 21849749 is about 4674.3715085560. The cubic root of 21849749 is about 279.5645826036.

The spelling of 21849749 in words is "twenty-one million, eight hundred forty-nine thousand, seven hundred forty-nine".