1021810021 has 2 divisors, whose sum is σ = 1021810022. Its totient is φ = 1021810020.

The previous prime is 1021809991. The next prime is 1021810037. The reversal of 1021810021 is 1200181201.

It is an a-pointer prime, because the next prime (1021810037) can be obtained adding 1021810021 to its sum of digits (16).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 731107521 + 290702500 = 27039^2 + 17050^2 .

It is an emirp because it is prime and its reverse (1200181201) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1021810021 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1021809977 and 1021810004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1021810421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 510905010 + 510905011.

It is an arithmetic number, because the mean of its divisors is an integer number (510905011).

Almost surely, 2^1021810021 is an apocalyptic number.

It is an amenable number.

1021810021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1021810021 is an equidigital number, since it uses as much as digits as its factorization.

1021810021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 16.

The square root of 1021810021 is about 31965.7632632165. The cubic root of 1021810021 is about 1007.2177852360.

Adding to 1021810021 its reverse (1200181201), we get a palindrome (2221991222).

The spelling of 1021810021 in words is "one billion, twenty-one million, eight hundred ten thousand, twenty-one".