21451433849 has 2 divisors, whose sum is σ = 21451433850. Its totient is φ = 21451433848.

The previous prime is 21451433831. The next prime is 21451433873. The reversal of 21451433849 is 94833415412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12034090000 + 9417343849 = 109700^2 + 97043^2 .

It is a cyclic number.

It is not a de Polignac number, because 21451433849 - 2⁸ = 21451433593 is a prime.

It is not a weakly prime, because it can be changed into another prime (21451433879) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10725716924 + 10725716925.

It is an arithmetic number, because the mean of its divisors is an integer number (10725716925).

Almost surely, 2^21451433849 is an apocalyptic number.

It is an amenable number.

21451433849 is a deficient number, since it is larger than the sum of its proper divisors (1).

21451433849 is an equidigital number, since it uses as much as digits as its factorization.

21451433849 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 414720, while the sum is 44.

The spelling of 21451433849 in words is "twenty-one billion, four hundred fifty-one million, four hundred thirty-three thousand, eight hundred forty-nine".