20011001 has 2 divisors, whose sum is σ = 20011002. Its totient is φ = 20011000.

The previous prime is 20010967. The next prime is 20011007. The reversal of 20011001 is 10011002.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18318400 + 1692601 = 4280^2 + 1301^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20011001 is a prime.

It is a super-2 number, since 2×20011001² = 800880322044002, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20011007) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10005500 + 10005501.

It is an arithmetic number, because the mean of its divisors is an integer number (10005501).

Almost surely, 2^20011001 is an apocalyptic number.

It is an amenable number.

20011001 is a deficient number, since it is larger than the sum of its proper divisors (1).

20011001 is an equidigital number, since it uses as much as digits as its factorization.

20011001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2, while the sum is 5.

The square root of 20011001 is about 4473.3657351037. The cubic root of 20011001 is about 271.4915213842.

Adding to 20011001 its reverse (10011002), we get a palindrome (30022003).

Subtracting from 20011001 its reverse (10011002), we obtain a palindrome (9999999).

Multiplying 20011001 by its reverse (10011002), we get a palindrome (200330171033002).

It can be divided in two parts, 2001 and 1001, that multiplied together give a triangular number (2003001 = T₂₀₀₁).

The spelling of 20011001 in words is "twenty million, eleven thousand, one".