210100021 has 12 divisors (see below), whose sum is σ = 216559200. Its totient is φ = 203825160.

The previous prime is 210100013. The next prime is 210100057. The reversal of 210100021 is 120001012.

It is not a de Polignac number, because 210100021 - 2³ = 210100013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 210099977 and 210100013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (210100721) 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, 367666 + ... + 368236.

It is an arithmetic number, because the mean of its divisors is an integer number (18046600).

Almost surely, 2^210100021 is an apocalyptic number.

It is an amenable number.

210100021 is a deficient number, since it is larger than the sum of its proper divisors (6459179).

210100021 is an equidigital number, since it uses as much as digits as its factorization.

210100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 856 (or 813 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 210100021 is about 14494.8273877270. The cubic root of 210100021 is about 594.4865480787.

Adding to 210100021 its reverse (120001012), we get a palindrome (330101033).

Subtracting from 210100021 its reverse (120001012), we obtain a palindrome (90099009).

The spelling of 210100021 in words is "two hundred ten million, one hundred thousand, twenty-one".