20001121997 has 2 divisors, whose sum is σ = 20001121998. Its totient is φ = 20001121996.

The previous prime is 20001121991. The next prime is 20001122041. The reversal of 20001121997 is 79912110002.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11930974441 + 8070147556 = 109229^2 + 89834^2 .

It is a cyclic number.

It is not a de Polignac number, because 20001121997 - 2¹² = 20001117901 is a prime.

It is a super-2 number, since 2×20001121997² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20001121991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10000560998 + 10000560999.

It is an arithmetic number, because the mean of its divisors is an integer number (10000560999).

Almost surely, 2^20001121997 is an apocalyptic number.

It is an amenable number.

20001121997 is a deficient number, since it is larger than the sum of its proper divisors (1).

20001121997 is an equidigital number, since it uses as much as digits as its factorization.

20001121997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2268, while the sum is 32.

Adding to 20001121997 its reverse (79912110002), we get a palindrome (99913231999).

The spelling of 20001121997 in words is "twenty billion, one million, one hundred twenty-one thousand, nine hundred ninety-seven".