1021005 has 20 divisors (see below), whose sum is σ = 1830972. Its totient is φ = 544320.

The previous prime is 1021001. The next prime is 1021019. The reversal of 1021005 is 5001201.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 110889 + 910116 = 333^2 + 954^2 .

It is not a de Polignac number, because 1021005 - 2² = 1021001 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1021001) 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 19 ways as a sum of consecutive naturals, for example, 856 + ... + 1665.

2^1021005 is an apocalyptic number.

1021005 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1021005 is a deficient number, since it is larger than the sum of its proper divisors (809967).

1021005 is an equidigital number, since it uses as much as digits as its factorization.

1021005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2538 (or 2529 counting only the distinct ones).

The product of its (nonzero) digits is 10, while the sum is 9.

The square root of 1021005 is about 1010.4479204788. The cubic root of 1021005 is about 100.6953207516.

Adding to 1021005 its reverse (5001201), we get a palindrome (6022206).

The spelling of 1021005 in words is "one million, twenty-one thousand, five".