1021020021 has 24 divisors (see below), whose sum is σ = 1690529984. Its totient is φ = 581696640.

The previous prime is 1021020019. The next prime is 1021020029. The reversal of 1021020021 is 1200201201.

It is not a de Polignac number, because 1021020021 - 2¹ = 1021020019 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 = 1021019985 and 1021020012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1021020029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2815 + ... + 45276.

Almost surely, 2^1021020021 is an apocalyptic number.

It is an amenable number.

1021020021 is a deficient number, since it is larger than the sum of its proper divisors (669509963).

1021020021 is a wasteful number, since it uses less digits than its factorization.

1021020021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48441 (or 48438 counting only the distinct ones).

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

The square root of 1021020021 is about 31953.4039031838. The cubic root of 1021020021 is about 1006.9581455820.

Adding to 1021020021 its reverse (1200201201), we get a palindrome (2221221222).

The spelling of 1021020021 in words is "one billion, twenty-one million, twenty thousand, twenty-one".