20508197993 has 2 divisors, whose sum is σ = 20508197994. Its totient is φ = 20508197992.

The previous prime is 20508197971. The next prime is 20508198001. The reversal of 20508197993 is 39979180502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14488455424 + 6019742569 = 120368^2 + 77587^2 .

It is a cyclic number.

It is not a de Polignac number, because 20508197993 - 2⁸ = 20508197737 is a prime.

It is not a weakly prime, because it can be changed into another prime (20508197923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10254098996 + 10254098997.

It is an arithmetic number, because the mean of its divisors is an integer number (10254098997).

Almost surely, 2^20508197993 is an apocalyptic number.

It is an amenable number.

20508197993 is a deficient number, since it is larger than the sum of its proper divisors (1).

20508197993 is an equidigital number, since it uses as much as digits as its factorization.

20508197993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1224720, while the sum is 53.

The spelling of 20508197993 in words is "twenty billion, five hundred eight million, one hundred ninety-seven thousand, nine hundred ninety-three".