211404440021 has 4 divisors (see below), whose sum is σ = 211863018444. Its totient is φ = 210945861600.

The previous prime is 211404440003. The next prime is 211404440029. The reversal of 211404440021 is 120044404112.

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 82351780900 + 129052659121 = 286970^2 + 359239^2 .

It is a cyclic number.

It is not a de Polignac number, because 211404440021 - 2¹⁸ = 211404177877 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211404440029) 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, 229288520 + ... + 229289441.

It is an arithmetic number, because the mean of its divisors is an integer number (52965754611).

Almost surely, 2^211404440021 is an apocalyptic number.

It is an amenable number.

211404440021 is a deficient number, since it is larger than the sum of its proper divisors (458578423).

211404440021 is an equidigital number, since it uses as much as digits as its factorization.

211404440021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 458578422.

The product of its (nonzero) digits is 1024, while the sum is 23.

Adding to 211404440021 its reverse (120044404112), we get a palindrome (331448844133).

The spelling of 211404440021 in words is "two hundred eleven billion, four hundred four million, four hundred forty thousand, twenty-one".