1021000220021 has 4 divisors (see below), whose sum is σ = 1021009713612. Its totient is φ = 1020990726432.

The previous prime is 1021000219991. The next prime is 1021000220027. The reversal of 1021000220021 is 1200220001201.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 730221520900 + 290778699121 = 854530^2 + 539239^2 .

It is a cyclic number.

It is not a de Polignac number, because 1021000220021 - 2⁶ = 1021000219957 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1021000219984 and 1021000220011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1021000220027) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4583606 + ... + 4801191.

It is an arithmetic number, because the mean of its divisors is an integer number (255252428403).

Almost surely, 2^{1021000220021} is an apocalyptic number.

It is an amenable number.

1021000220021 is a deficient number, since it is larger than the sum of its proper divisors (9493591).

1021000220021 is an equidigital number, since it uses as much as digits as its factorization.

1021000220021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9493590.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 1021000220021 its reverse (1200220001201), we get a palindrome (2221220221222).

The spelling of 1021000220021 in words is "one trillion, twenty-one billion, two hundred twenty thousand, twenty-one".