210806421 has 32 divisors (see below), whose sum is σ = 330670080. Its totient is φ = 116962176.

The previous prime is 210806413. The next prime is 210806441. The reversal of 210806421 is 124608012.

It is not a de Polignac number, because 210806421 - 2³ = 210806413 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 210806391 and 210806400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (210806441) 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, 134440 + ... + 135998.

It is an arithmetic number, because the mean of its divisors is an integer number (10333440).

Almost surely, 2^210806421 is an apocalyptic number.

210806421 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

210806421 is a deficient number, since it is larger than the sum of its proper divisors (119863659).

210806421 is a wasteful number, since it uses less digits than its factorization.

210806421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1753.

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 210806421 is about 14519.1742533796. The cubic root of 210806421 is about 595.1520652689.

The spelling of 210806421 in words is "two hundred ten million, eight hundred six thousand, four hundred twenty-one".