20851494049 has 2 divisors, whose sum is σ = 20851494050. Its totient is φ = 20851494048.

The previous prime is 20851494047. The next prime is 20851494127. The reversal of 20851494049 is 94049415802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10887461649 + 9964032400 = 104343^2 + 99820^2 .

It is a cyclic number.

It is not a de Polignac number, because 20851494049 - 2¹ = 20851494047 is a prime.

Together with 20851494047, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20851494047) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10425747024 + 10425747025.

It is an arithmetic number, because the mean of its divisors is an integer number (10425747025).

Almost surely, 2^20851494049 is an apocalyptic number.

It is an amenable number.

20851494049 is a deficient number, since it is larger than the sum of its proper divisors (1).

20851494049 is an equidigital number, since it uses as much as digits as its factorization.

20851494049 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 414720, while the sum is 46.

The spelling of 20851494049 in words is "twenty billion, eight hundred fifty-one million, four hundred ninety-four thousand, forty-nine".