20897012491 has 2 divisors, whose sum is σ = 20897012492. Its totient is φ = 20897012490.

The previous prime is 20897012431. The next prime is 20897012501. The reversal of 20897012491 is 19421079802.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20897012491 - 2¹⁹ = 20896488203 is a prime.

It is not a weakly prime, because it can be changed into another prime (20897012431) 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, 10448506245 + 10448506246.

It is an arithmetic number, because the mean of its divisors is an integer number (10448506246).

Almost surely, 2^20897012491 is an apocalyptic number.

20897012491 is a deficient number, since it is larger than the sum of its proper divisors (1).

20897012491 is an equidigital number, since it uses as much as digits as its factorization.

20897012491 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72576, while the sum is 43.

The spelling of 20897012491 in words is "twenty billion, eight hundred ninety-seven million, twelve thousand, four hundred ninety-one".