21849491 has 2 divisors, whose sum is σ = 21849492. Its totient is φ = 21849490.

The previous prime is 21849473. The next prime is 21849511. The reversal of 21849491 is 19494812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21849491 - 2⁶ = 21849427 is a prime.

It is a super-3 number, since 3×21849491³ (a number of 23 digits) contains 333 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21840491) 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, 10924745 + 10924746.

It is an arithmetic number, because the mean of its divisors is an integer number (10924746).

Almost surely, 2^21849491 is an apocalyptic number.

21849491 is a deficient number, since it is larger than the sum of its proper divisors (1).

21849491 is an equidigital number, since it uses as much as digits as its factorization.

21849491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20736, while the sum is 38.

The square root of 21849491 is about 4674.3439111815. The cubic root of 21849491 is about 279.5634822409.

The spelling of 21849491 in words is "twenty-one million, eight hundred forty-nine thousand, four hundred ninety-one".