20129717997 has 40 divisors (see below), whose sum is σ = 30639038232. Its totient is φ = 13167100800.

The previous prime is 20129717989. The next prime is 20129718019. The reversal of 20129717997 is 79971792102.

It can be written as a sum of positive squares in 4 ways, for example, as 604127241 + 19525590756 = 24579^2 + 139734^2 .

It is not a de Polignac number, because 20129717997 - 2³ = 20129717989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20129717957) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 2075323 + ... + 2084999.

Almost surely, 2^20129717997 is an apocalyptic number.

20129717997 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

20129717997 is a deficient number, since it is larger than the sum of its proper divisors (10509320235).

20129717997 is an equidigital number, since it uses as much as digits as its factorization.

20129717997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10171 (or 10162 counting only the distinct ones).

The product of its (nonzero) digits is 1000188, while the sum is 54.

The spelling of 20129717997 in words is "twenty billion, one hundred twenty-nine million, seven hundred seventeen thousand, nine hundred ninety-seven".