210031021 has 4 divisors (see below), whose sum is σ = 217273500. Its totient is φ = 202788544.

The previous prime is 210031013. The next prime is 210031037. The reversal of 210031021 is 120130012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 63282025 + 146748996 = 7955^2 + 12114^2 .

It is a cyclic number.

It is not a de Polignac number, because 210031021 - 2³ = 210031013 is a prime.

It is a super-2 number, since 2×210031021² = 88226059564604882, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 210030989 and 210031007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (210037021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3621196 + ... + 3621253.

It is an arithmetic number, because the mean of its divisors is an integer number (54318375).

Almost surely, 2^210031021 is an apocalyptic number.

It is an amenable number.

210031021 is a deficient number, since it is larger than the sum of its proper divisors (7242479).

210031021 is an equidigital number, since it uses as much as digits as its factorization.

210031021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7242478.

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 210031021 is about 14492.4470328513. The cubic root of 210031021 is about 594.4214615183.

Adding to 210031021 its reverse (120130012), we get a palindrome (330161033).

The spelling of 210031021 in words is "two hundred ten million, thirty-one thousand, twenty-one".