212231661 has 4 divisors (see below), whose sum is σ = 282975552. Its totient is φ = 141487772.

The previous prime is 212231633. The next prime is 212231671. The reversal of 212231661 is 166132212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 212231661 - 2⁵ = 212231629 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212231671) 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, 35371941 + ... + 35371946.

It is an arithmetic number, because the mean of its divisors is an integer number (70743888).

Almost surely, 2^212231661 is an apocalyptic number.

It is an amenable number.

212231661 is a deficient number, since it is larger than the sum of its proper divisors (70743891).

212231661 is an equidigital number, since it uses as much as digits as its factorization.

212231661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70743890.

The product of its digits is 864, while the sum is 24.

The square root of 212231661 is about 14568.1728778869. The cubic root of 212231661 is about 596.4903073478.

Adding to 212231661 its reverse (166132212), we get a palindrome (378363873).

The spelling of 212231661 in words is "two hundred twelve million, two hundred thirty-one thousand, six hundred sixty-one".