661334562221 has 4 divisors (see below), whose sum is σ = 662291631744. Its totient is φ = 660377492700.

The previous prime is 661334562209. The next prime is 661334562223. The reversal of 661334562221 is 122265433166.

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 661334562221 - 2³⁰ = 660260820397 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 (661334562223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 478533725 + ... + 478535106.

It is an arithmetic number, because the mean of its divisors is an integer number (165572907936).

Almost surely, 2^661334562221 is an apocalyptic number.

It is an amenable number.

661334562221 is a deficient number, since it is larger than the sum of its proper divisors (957069523).

661334562221 is an equidigital number, since it uses as much as digits as its factorization.

661334562221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 957069522.

The product of its digits is 311040, while the sum is 41.

Adding to 661334562221 its reverse (122265433166), we get a palindrome (783599995387).

The spelling of 661334562221 in words is "six hundred sixty-one billion, three hundred thirty-four million, five hundred sixty-two thousand, two hundred twenty-one".