21894891049 has 2 divisors, whose sum is σ = 21894891050. Its totient is φ = 21894891048.

The previous prime is 21894890951. The next prime is 21894891061. The reversal of 21894891049 is 94019849812.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21083040000 + 811851049 = 145200^2 + 28493^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21894891049 is a prime.

It is not a weakly prime, because it can be changed into another prime (21894891089) 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, 10947445524 + 10947445525.

It is an arithmetic number, because the mean of its divisors is an integer number (10947445525).

Almost surely, 2^21894891049 is an apocalyptic number.

It is an amenable number.

21894891049 is a deficient number, since it is larger than the sum of its proper divisors (1).

21894891049 is an equidigital number, since it uses as much as digits as its factorization.

21894891049 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1492992, while the sum is 55.

The spelling of 21894891049 in words is "twenty-one billion, eight hundred ninety-four million, eight hundred ninety-one thousand, forty-nine".