1001021 has 12 divisors (see below), whose sum is σ = 1203840. Its totient is φ = 829080.

The previous prime is 1001017. The next prime is 1001023. The reversal of 1001021 is 1201001.

It is a happy number.

It is not a de Polignac number, because 1001021 - 2² = 1001017 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1000996 and 1001014.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1001023) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1190 + ... + 1848.

It is an arithmetic number, because the mean of its divisors is an integer number (100320).

2^1001021 is an apocalyptic number.

It is an amenable number.

1001021 is a deficient number, since it is larger than the sum of its proper divisors (202819).

1001021 is an equidigital number, since it uses as much as digits as its factorization.

1001021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 704 (or 697 counting only the distinct ones).

The product of its (nonzero) digits is 2, while the sum is 5.

The square root of 1001021 is about 1000.5103697614. The cubic root of 1001021 is about 100.0340217572.

Adding to 1001021 its reverse (1201001), we get a palindrome (2202022).

Multiplying 1001021 by its reverse (1201001), we get a palindrome (1202227222021).

The spelling of 1001021 in words is "one million, one thousand, twenty-one".