1021200021 has 16 divisors (see below), whose sum is σ = 1514414400. Its totient is φ = 680113584.

The previous prime is 1021200017. The next prime is 1021200031. The reversal of 1021200021 is 1200021201.

It is not a de Polignac number, because 1021200021 - 2² = 1021200017 is a prime.

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

It is a junction number, because it is equal to n+sod(n) for n = 1021199976 and 1021200012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1021200031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8955 + ... + 46071.

It is an arithmetic number, because the mean of its divisors is an integer number (94650900).

Almost surely, 2^1021200021 is an apocalyptic number.

It is an amenable number.

1021200021 is a deficient number, since it is larger than the sum of its proper divisors (493214379).

1021200021 is a wasteful number, since it uses less digits than its factorization.

1021200021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38145 (or 38139 counting only the distinct ones).

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

The square root of 1021200021 is about 31956.2203803892. The cubic root of 1021200021 is about 1007.0173157623.

Adding to 1021200021 its reverse (1200021201), we get a palindrome (2221221222).

The spelling of 1021200021 in words is "one billion, twenty-one million, two hundred thousand, twenty-one".