111916821 has 16 divisors (see below), whose sum is σ = 158128640. Its totient is φ = 70210800.

The previous prime is 111916801. The next prime is 111916843. The reversal of 111916821 is 128619111.

111916821 = 2418² + 2419² + ... + 2436².

It is a happy number.

It is not a de Polignac number, because 111916821 - 2¹⁸ = 111654677 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (111916801) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2106 + ... + 15108.

It is an arithmetic number, because the mean of its divisors is an integer number (9883040).

Almost surely, 2^111916821 is an apocalyptic number.

It is an amenable number.

111916821 is a deficient number, since it is larger than the sum of its proper divisors (46211819).

111916821 is a wasteful number, since it uses less digits than its factorization.

111916821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13176.

The product of its digits is 864, while the sum is 30.

The square root of 111916821 is about 10579.0746759818. The cubic root of 111916821 is about 481.9090939825.

The spelling of 111916821 in words is "one hundred eleven million, nine hundred sixteen thousand, eight hundred twenty-one".