212221645 has 4 divisors (see below), whose sum is σ = 254665980. Its totient is φ = 169777312.

The previous prime is 212221613. The next prime is 212221649. The reversal of 212221645 is 546122212.

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 142515844 + 69705801 = 11938^2 + 8349^2 .

It is a cyclic number.

It is not a de Polignac number, because 212221645 - 2⁵ = 212221613 is a prime.

It is a super-3 number, since 3×212221645³ (a number of 26 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212221649) 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, 21222160 + ... + 21222169.

It is an arithmetic number, because the mean of its divisors is an integer number (63666495).

Almost surely, 2^212221645 is an apocalyptic number.

It is an amenable number.

212221645 is a deficient number, since it is larger than the sum of its proper divisors (42444335).

212221645 is an equidigital number, since it uses as much as digits as its factorization.

212221645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42444334.

The product of its digits is 1920, while the sum is 25.

The square root of 212221645 is about 14567.8291107495. The cubic root of 212221645 is about 596.4809236695.

Adding to 212221645 its reverse (546122212), we get a palindrome (758343857).

The spelling of 212221645 in words is "two hundred twelve million, two hundred twenty-one thousand, six hundred forty-five".