211312505 has 4 divisors (see below), whose sum is σ = 253575012. Its totient is φ = 169050000.

The previous prime is 211312501. The next prime is 211312579. The reversal of 211312505 is 505213112.

It is a happy number.

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 111851776 + 99460729 = 10576^2 + 9973^2 .

It is not a de Polignac number, because 211312505 - 2² = 211312501 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (211312501) 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, 21131246 + ... + 21131255.

It is an arithmetic number, because the mean of its divisors is an integer number (63393753).

Almost surely, 2^211312505 is an apocalyptic number.

It is an amenable number.

211312505 is a deficient number, since it is larger than the sum of its proper divisors (42262507).

211312505 is an equidigital number, since it uses as much as digits as its factorization.

211312505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42262506.

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 211312505 is about 14536.5919320864. The cubic root of 211312505 is about 595.6279461410.

Adding to 211312505 its reverse (505213112), we get a palindrome (716525617).

The spelling of 211312505 in words is "two hundred eleven million, three hundred twelve thousand, five hundred five".