210105021 has 32 divisors (see below), whose sum is σ = 340172800. Its totient is φ = 112674240.

The previous prime is 210105001. The next prime is 210105037. The reversal of 210105021 is 120501012.

It is not a de Polignac number, because 210105021 - 2⁷ = 210104893 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 210104988 and 210105006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (210105001) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 41076 + ... + 45906.

It is an arithmetic number, because the mean of its divisors is an integer number (10630400).

Almost surely, 2^210105021 is an apocalyptic number.

210105021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

210105021 is a deficient number, since it is larger than the sum of its proper divisors (130067779).

210105021 is a wasteful number, since it uses less digits than its factorization.

210105021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4969.

The product of its (nonzero) digits is 20, while the sum is 12.

The square root of 210105021 is about 14494.9998620214. Note that the first 3 decimals coincide. The cubic root of 210105021 is about 594.4912639424.

Adding to 210105021 its reverse (120501012), we get a palindrome (330606033).

The spelling of 210105021 in words is "two hundred ten million, one hundred five thousand, twenty-one".