210213721 has 16 divisors (see below), whose sum is σ = 240278400. Its totient is φ = 182710528.

The previous prime is 210213719. The next prime is 210213727. The reversal of 210213721 is 127312012.

It is not a de Polignac number, because 210213721 - 2¹ = 210213719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (210213727) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2070 + ... + 20608.

It is an arithmetic number, because the mean of its divisors is an integer number (15017400).

Almost surely, 2^210213721 is an apocalyptic number.

It is an amenable number.

210213721 is a deficient number, since it is larger than the sum of its proper divisors (30064679).

210213721 is a wasteful number, since it uses less digits than its factorization.

210213721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18608.

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 210213721 is about 14498.7489460298. The cubic root of 210213721 is about 594.5937683298.

Adding to 210213721 its reverse (127312012), we get a palindrome (337525733).

It can be divided in two parts, 21021 and 3721, that added together give a palindrome (24742).

The spelling of 210213721 in words is "two hundred ten million, two hundred thirteen thousand, seven hundred twenty-one".