211520421 has 24 divisors (see below), whose sum is σ = 349599744. Its totient is φ = 120722400.

The previous prime is 211520411. The next prime is 211520447. The reversal of 211520421 is 124025112.

It is not a de Polignac number, because 211520421 - 2¹⁰ = 211519397 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 211520394 and 211520403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211520411) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 71055 + ... + 73971.

It is an arithmetic number, because the mean of its divisors is an integer number (14566656).

Almost surely, 2^211520421 is an apocalyptic number.

211520421 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

211520421 is a deficient number, since it is larger than the sum of its proper divisors (138079323).

211520421 is a wasteful number, since it uses less digits than its factorization.

211520421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4081 (or 4078 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 211520421 is about 14543.7416437449. The cubic root of 211520421 is about 595.8232335039.

Adding to 211520421 its reverse (124025112), we get a palindrome (335545533).

The spelling of 211520421 in words is "two hundred eleven million, five hundred twenty thousand, four hundred twenty-one".