210121290 has 80 divisors (see below), whose sum is σ = 569111400. Its totient is φ = 55624320.

The previous prime is 210121283. The next prime is 210121291. The reversal of 210121290 is 92121012.

It can be written as a sum of positive squares in 4 ways, for example, as 50680161 + 159441129 = 7119^2 + 12627^2 .

It is a super-2 number, since 2×210121290² = 88301913022528200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (210121291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 119820 + ... + 121560.

Almost surely, 2^210121290 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 210121290, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (284555700).

210121290 is an abundant number, since it is smaller than the sum of its proper divisors (358990110).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

210121290 is a wasteful number, since it uses less digits than its factorization.

210121290 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1909 (or 1900 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 210121290 is about 14495.5610446785. The cubic root of 210121290 is about 594.5066079018.

The spelling of 210121290 in words is "two hundred ten million, one hundred twenty-one thousand, two hundred ninety".