20891576393 has 2 divisors, whose sum is σ = 20891576394. Its totient is φ = 20891576392.

The previous prime is 20891576383. The next prime is 20891576443. The reversal of 20891576393 is 39367519802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12808127929 + 8083448464 = 113173^2 + 89908^2 .

It is a cyclic number.

It is not a de Polignac number, because 20891576393 - 2⁸ = 20891576137 is a prime.

It is a super-3 number, since 3×20891576393³ (a number of 32 digits) contains 333 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20891576323) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10445788196 + 10445788197.

It is an arithmetic number, because the mean of its divisors is an integer number (10445788197).

Almost surely, 2^20891576393 is an apocalyptic number.

It is an amenable number.

20891576393 is a deficient number, since it is larger than the sum of its proper divisors (1).

20891576393 is an equidigital number, since it uses as much as digits as its factorization.

20891576393 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2449440, while the sum is 53.

The spelling of 20891576393 in words is "twenty billion, eight hundred ninety-one million, five hundred seventy-six thousand, three hundred ninety-three".