1210020021 has 12 divisors (see below), whose sum is σ = 1997493472. Its totient is φ = 691439976.

The previous prime is 1210020013. The next prime is 1210020061. The reversal of 1210020021 is 1200200121.

It is not a de Polignac number, because 1210020021 - 2³ = 1210020013 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 = 1210019985 and 1210020012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1210020061) 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, 9603271 + ... + 9603396.

Almost surely, 2^1210020021 is an apocalyptic number.

It is an amenable number.

1210020021 is a deficient number, since it is larger than the sum of its proper divisors (787473451).

1210020021 is a wasteful number, since it uses less digits than its factorization.

1210020021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19206680 (or 19206677 counting only the distinct ones).

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

The square root of 1210020021 is about 34785.3420423028. The cubic root of 1210020021 is about 1065.6081139855.

Adding to 1210020021 its reverse (1200200121), we get a palindrome (2410220142).

The spelling of 1210020021 in words is "one billion, two hundred ten million, twenty thousand, twenty-one".