20001549631891 has 2 divisors, whose sum is σ = 20001549631892. Its totient is φ = 20001549631890.

The previous prime is 20001549631793. The next prime is 20001549631993. The reversal of 20001549631891 is 19813694510002.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20001549631891 - 2³⁵ = 19967189893523 is a prime.

It is not a weakly prime, because it can be changed into another prime (20001549632891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10000774815945 + 10000774815946.

It is an arithmetic number, because the mean of its divisors is an integer number (10000774815946).

Almost surely, 2^{20001549631891} is an apocalyptic number.

20001549631891 is a deficient number, since it is larger than the sum of its proper divisors (1).

20001549631891 is an equidigital number, since it uses as much as digits as its factorization.

20001549631891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 466560, while the sum is 49.

The spelling of 20001549631891 in words is "twenty trillion, one billion, five hundred forty-nine million, six hundred thirty-one thousand, eight hundred ninety-one".