66835721 has 8 divisors (see below), whose sum is σ = 73050624. Its totient is φ = 60874560.

The previous prime is 66835709. The next prime is 66835729. The reversal of 66835721 is 12753866.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66835721 - 2¹⁰ = 66834697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66835729) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 62885 + ... + 63938.

It is an arithmetic number, because the mean of its divisors is an integer number (9131328).

Almost surely, 2^66835721 is an apocalyptic number.

It is an amenable number.

66835721 is a deficient number, since it is larger than the sum of its proper divisors (6214903).

66835721 is a wasteful number, since it uses less digits than its factorization.

66835721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126871.

The product of its digits is 60480, while the sum is 38.

The square root of 66835721 is about 8175.3116760158. The cubic root of 66835721 is about 405.8225846044.

The spelling of 66835721 in words is "sixty-six million, eight hundred thirty-five thousand, seven hundred twenty-one".