66822721 has 12 divisors (see below), whose sum is σ = 78299760. Its totient is φ = 56858760.

The previous prime is 66822689. The next prime is 66822739. The reversal of 66822721 is 12722866.

It is not a de Polignac number, because 66822721 - 2⁵ = 66822689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66822781) 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, 1906 + ... + 11716.

It is an arithmetic number, because the mean of its divisors is an integer number (6524980).

Almost surely, 2^66822721 is an apocalyptic number.

It is an amenable number.

66822721 is a deficient number, since it is larger than the sum of its proper divisors (11477039).

66822721 is a wasteful number, since it uses less digits than its factorization.

66822721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9964 (or 9957 counting only the distinct ones).

The product of its digits is 16128, while the sum is 34.

The square root of 66822721 is about 8174.5165606291. The cubic root of 66822721 is about 405.7962711520.

The spelling of 66822721 in words is "sixty-six million, eight hundred twenty-two thousand, seven hundred twenty-one".