210399121 has 4 divisors (see below), whose sum is σ = 210536500. Its totient is φ = 210261744.

The previous prime is 210399113. The next prime is 210399149. The reversal of 210399121 is 121993012.

210399121 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 70308225 + 140090896 = 8385^2 + 11836^2 .

It is a cyclic number.

It is not a de Polignac number, because 210399121 - 2³ = 210399113 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 210399121.

It is not an unprimeable number, because it can be changed into a prime (210379121) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66366 + ... + 69463.

It is an arithmetic number, because the mean of its divisors is an integer number (52634125).

Almost surely, 2^210399121 is an apocalyptic number.

It is an amenable number.

210399121 is a deficient number, since it is larger than the sum of its proper divisors (137379).

210399121 is a wasteful number, since it uses less digits than its factorization.

210399121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137378.

The product of its (nonzero) digits is 972, while the sum is 28.

The square root of 210399121 is about 14505.1411920050. The cubic root of 210399121 is about 594.7685195173.

It can be divided in two parts, 2103991 and 21, that added together give a palindrome (2104012).

The spelling of 210399121 in words is "two hundred ten million, three hundred ninety-nine thousand, one hundred twenty-one".