111661021 has 4 divisors (see below), whose sum is σ = 116515872. Its totient is φ = 106806172.

The previous prime is 111661007. The next prime is 111661037. The reversal of 111661021 is 120166111.

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 111661021 - 2¹³ = 111652829 is a prime.

It is a super-2 number, since 2×111661021² = 24936367221524882, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 111661021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (111661051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2427391 + ... + 2427436.

It is an arithmetic number, because the mean of its divisors is an integer number (29128968).

Almost surely, 2^111661021 is an apocalyptic number.

It is an amenable number.

111661021 is a deficient number, since it is larger than the sum of its proper divisors (4854851).

111661021 is an equidigital number, since it uses as much as digits as its factorization.

111661021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4854850.

The product of its (nonzero) digits is 72, while the sum is 19.

The square root of 111661021 is about 10566.9778555649. The cubic root of 111661021 is about 481.5416592432.

The spelling of 111661021 in words is "one hundred eleven million, six hundred sixty-one thousand, twenty-one".