111281620921 has 3 divisors (see below), whose sum is σ = 111281954511. Its totient is φ = 111281287332.

The previous prime is 111281620909. The next prime is 111281620969. The reversal of 111281620921 is 129026182111.

The square root of 111281620921 is 333589.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 129026182111 = 19391 ⋅6653921.

It can be written as a sum of positive squares in only one way, i.e., 95721553321 + 15560067600 = 309389^2 + 124740^2 .

It is not a de Polignac number, because 111281620921 - 2⁹ = 111281620409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (111281620621) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 166795 + ... + 500383.

It is an arithmetic number, because the mean of its divisors is an integer number (37093984837).

Almost surely, 2^111281620921 is an apocalyptic number.

111281620921 is the 333589-th square number.

111281620921 is the 166795-th centered octagonal number.

It is an amenable number.

111281620921 is a deficient number, since it is larger than the sum of its proper divisors (333590).

111281620921 is an frugal number, since it uses more digits than its factorization.

111281620921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 667178 (or 333589 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 34.

The spelling of 111281620921 in words is "one hundred eleven billion, two hundred eighty-one million, six hundred twenty thousand, nine hundred twenty-one".