20021001997 has 2 divisors, whose sum is σ = 20021001998. Its totient is φ = 20021001996.

The previous prime is 20021001989. The next prime is 20021002019. The reversal of 20021001997 is 79910012002.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14896446601 + 5124555396 = 122051^2 + 71586^2 .

It is a cyclic number.

It is not a de Polignac number, because 20021001997 - 2³ = 20021001989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20021001907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10010500998 + 10010500999.

It is an arithmetic number, because the mean of its divisors is an integer number (10010500999).

Almost surely, 2^20021001997 is an apocalyptic number.

It is an amenable number.

20021001997 is a deficient number, since it is larger than the sum of its proper divisors (1).

20021001997 is an equidigital number, since it uses as much as digits as its factorization.

20021001997 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2268, while the sum is 31.

Adding to 20021001997 its reverse (79910012002), we get a palindrome (99931013999).

The spelling of 20021001997 in words is "twenty billion, twenty-one million, one thousand, nine hundred ninety-seven".