66111921 has 12 divisors (see below), whose sum is σ = 95620980. Its totient is φ = 44016480.

The previous prime is 66111911. The next prime is 66111923. The reversal of 66111921 is 12911166.

It can be written as a sum of positive squares in 2 ways, for example, as 55711296 + 10400625 = 7464^2 + 3225^2 .

It is not a de Polignac number, because 66111921 - 2¹³ = 66103729 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66111923) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3031 + ... + 11891.

It is an arithmetic number, because the mean of its divisors is an integer number (7968415).

Almost surely, 2^66111921 is an apocalyptic number.

It is an amenable number.

66111921 is a deficient number, since it is larger than the sum of its proper divisors (29509059).

66111921 is a wasteful number, since it uses less digits than its factorization.

66111921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9696 (or 9693 counting only the distinct ones).

The product of its digits is 648, while the sum is 27.

The square root of 66111921 is about 8130.9237482589. The cubic root of 66111921 is about 404.3523072133.

The spelling of 66111921 in words is "sixty-six million, one hundred eleven thousand, nine hundred twenty-one".