111563621661 has 4 divisors (see below), whose sum is σ = 148751495552. Its totient is φ = 74375747772.

The previous prime is 111563621591. The next prime is 111563621669. The reversal of 111563621661 is 166126365111.

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 not a de Polignac number, because 111563621661 - 2¹⁸ = 111563359517 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 (111563621669) 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, 18593936941 + ... + 18593936946.

It is an arithmetic number, because the mean of its divisors is an integer number (37187873888).

Almost surely, 2^111563621661 is an apocalyptic number.

It is an amenable number.

111563621661 is a deficient number, since it is larger than the sum of its proper divisors (37187873891).

111563621661 is an equidigital number, since it uses as much as digits as its factorization.

111563621661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37187873890.

The product of its digits is 38880, while the sum is 39.

Adding to 111563621661 its reverse (166126365111), we get a palindrome (277689986772).

The spelling of 111563621661 in words is "one hundred eleven billion, five hundred sixty-three million, six hundred twenty-one thousand, six hundred sixty-one".