2100021901 has 2 divisors, whose sum is σ = 2100021902. Its totient is φ = 2100021900.

The previous prime is 2100021893. The next prime is 2100021907. The reversal of 2100021901 is 1091200012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2072616676 + 27405225 = 45526^2 + 5235^2 .

It is a cyclic number.

It is not a de Polignac number, because 2100021901 - 2³ = 2100021893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2100021907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1050010950 + 1050010951.

It is an arithmetic number, because the mean of its divisors is an integer number (1050010951).

Almost surely, 2^2100021901 is an apocalyptic number.

It is an amenable number.

2100021901 is a deficient number, since it is larger than the sum of its proper divisors (1).

2100021901 is an equidigital number, since it uses as much as digits as its factorization.

2100021901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36, while the sum is 16.

The square root of 2100021901 is about 45825.9959084361. The cubic root of 2100021901 is about 1280.5836167124.

Adding to 2100021901 its reverse (1091200012), we get a palindrome (3191221913).

The spelling of 2100021901 in words is "two billion, one hundred million, twenty-one thousand, nine hundred one".