1004001021 has 16 divisors (see below), whose sum is σ = 1565694400. Its totient is φ = 634105584.

The previous prime is 1004001007. The next prime is 1004001041. The reversal of 1004001021 is 1201004001.

It is a happy number.

It is not a de Polignac number, because 1004001021 - 2⁹ = 1004000509 is a prime.

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

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1004000994 and 1004001012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1004001041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 978046 + ... + 979071.

It is an arithmetic number, because the mean of its divisors is an integer number (97855900).

Almost surely, 2^1004001021 is an apocalyptic number.

It is an amenable number.

1004001021 is a deficient number, since it is larger than the sum of its proper divisors (561693379).

1004001021 is a wasteful number, since it uses less digits than its factorization.

1004001021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1957145 (or 1957139 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 1004001021 is about 31685.9751467428. The cubic root of 1004001021 is about 1001.3318989243.

Adding to 1004001021 its reverse (1201004001), we get a palindrome (2205005022).

The spelling of 1004001021 in words is "one billion, four million, one thousand, twenty-one".