661166223631 has 4 divisors (see below), whose sum is σ = 663800352264. Its totient is φ = 658532095000.

The previous prime is 661166223629. The next prime is 661166223637. The reversal of 661166223631 is 136322661166.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 661166223631 - 2¹ = 661166223629 is a prime.

It is a super-2 number, since 2×661166223631² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661166223637) 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, 1317063940 + ... + 1317064441.

It is an arithmetic number, because the mean of its divisors is an integer number (165950088066).

Almost surely, 2^661166223631 is an apocalyptic number.

661166223631 is a deficient number, since it is larger than the sum of its proper divisors (2634128633).

661166223631 is a wasteful number, since it uses less digits than its factorization.

661166223631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2634128632.

The product of its digits is 279936, while the sum is 43.

Adding to 661166223631 its reverse (136322661166), we get a palindrome (797488884797).

The spelling of 661166223631 in words is "six hundred sixty-one billion, one hundred sixty-six million, two hundred twenty-three thousand, six hundred thirty-one".