1020001021 has 12 divisors (see below), whose sum is σ = 1142589780. Its totient is φ = 909068160.

The previous prime is 1020001013. The next prime is 1020001039. The reversal of 1020001021 is 1201000201.

It can be written as a sum of positive squares in 6 ways, for example, as 356680996 + 663320025 = 18886^2 + 25755^2 .

It is not a de Polignac number, because 1020001021 - 2³ = 1020001013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1020000995 and 1020001013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1020001001) 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, 99160 + ... + 108961.

It is an arithmetic number, because the mean of its divisors is an integer number (95215815).

Almost surely, 2^1020001021 is an apocalyptic number.

It is an amenable number.

1020001021 is a deficient number, since it is larger than the sum of its proper divisors (122588759).

1020001021 is a wasteful number, since it uses less digits than its factorization.

1020001021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 208176 (or 208163 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 1020001021 is about 31937.4548297137. The cubic root of 1020001021 is about 1006.6230454299.

Adding to 1020001021 its reverse (1201000201), we get a palindrome (2221001222).

The spelling of 1020001021 in words is "one billion, twenty million, one thousand, twenty-one".