66621161 has 4 divisors (see below), whose sum is σ = 66681300. Its totient is φ = 66561024.

The previous prime is 66621151. The next prime is 66621169. The reversal of 66621161 is 16112666.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16112666 = 2 ⋅8056333.

It can be written as a sum of positive squares in 2 ways, for example, as 15054400 + 51566761 = 3880^2 + 7181^2 .

It is a cyclic number.

It is not a de Polignac number, because 66621161 - 2⁶ = 66621097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66621169) 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, 28376 + ... + 30633.

It is an arithmetic number, because the mean of its divisors is an integer number (16670325).

Almost surely, 2^66621161 is an apocalyptic number.

It is an amenable number.

66621161 is a deficient number, since it is larger than the sum of its proper divisors (60139).

66621161 is a wasteful number, since it uses less digits than its factorization.

66621161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60138.

The product of its digits is 2592, while the sum is 29.

The square root of 66621161 is about 8162.1786919915. The cubic root of 66621161 is about 405.3878538200.

The spelling of 66621161 in words is "sixty-six million, six hundred twenty-one thousand, one hundred sixty-one".