1020021 has 4 divisors (see below), whose sum is σ = 1360032.
Its totient is φ = 680012.
The previous prime is 1020013. The next prime is 1020023. The reversal of 1020021 is 1200201.
It is a happy number.
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1200201 = 3 ⋅400067.
It is a cyclic number.
It is not a de Polignac number, because 1020021 - 23 = 1020013 is a prime.
It is a D-number.
1020021 is a lucky number.
It is a junction number, because it is equal to n+sod(n) for n = 1019991 and 1020009.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (1020023) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (11) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 170001 + ... + 170006.
It is an arithmetic number, because the mean of its divisors is an integer number (340008).
21020021 is an apocalyptic number.
It is an amenable number.
1020021 is a deficient number, since it is larger than the sum of its proper divisors (340011).
1020021 is an equidigital number, since it uses as much as digits as its factorization.
1020021 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 340010.
The product of its (nonzero) digits is 4, while the sum is 6.
The square root of 1020021 is about 1009.9608903319.
The cubic root of 1020021 is about 100.6629617708.
Adding to 1020021 its reverse (1200201), we get a palindrome (2220222).
The spelling of 1020021 in words is "one million, twenty thousand, twenty-one".